 Section 0 of an Essay Concerning Human Understanding by John Locke, Book 4 of Knowledge and Probability. This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer, please visit LibriVox.org. Recording by Gillian Hendry. Of Knowledge and Probability, Synopsis of the Fourth Book. Locke's review of the different sorts of ideas or appearances of what exists that can be entertained in a human understanding and of their relations to words leads in the fourth book to an investigation of the extent and validity of the knowledge that our ideas bring within our reach and into the nature of faith and probability by which ascent is extended beyond knowledge for the conduct of life. He finds, chapters one and two, that knowledge is either an intuitive, a demonstrative or a sensuous perception of absolute certainty in regard to one or other of four sorts of agreement or disagreement on the part of ideas. One, of each idea within itself as identical and different from every other. Two, in their abstract relations to one another. Three, in their necessary connections as qualities and powers coexisting in concrete substances. And four, as revelations to us of the final realities of existence. The unconditional certainty that constitutes knowledge is perceptible by man only in regard to the first, second and fourth of these four sorts. In all general propositions only in regard to the first and second. That is to say in identical propositions and in those which express abstract relations of simple or mixed modes in which nominal and real essences coincide. For example propositions in pure mathematics and abstract morality. Chapters three and five to eight. The fourth sort which express certainty as to realities of existence refer to any of three realities. For every man is able to perceive with absolute certainty that he himself exists, that God must exist and that finite beings other than himself exist. The first of these perceptions being awakened by all our ideas. The second as the consequence of perception of the first and the last in the reception of our simple ideas of sense. Chapters one section seven, two section fourteen, three section twenty one, four and nine to eleven. Agreement of the third sort of necessary coexistence of simple ideas as qualities and powers in particular substances with which all physical inquiry is concerned lies beyond human knowledge. For here the nominal and real essences are not coincident. General propositions of this sort are determined by analogies of experience in judgments that are more or less probable. Intellectually necessary science of nature presupposes omniscience. Man's interpretations of nature have to turn upon presumptions of probability. Chapters three sections nine to seventeen. Four sections eleven to seventeen. Six and fourteen to sixteen. In forming their stock of certainties and probabilities men employ the faculty of reason, faith in divine revelation and enthusiasm. Chapters seventeen to nineteen. Much misled by the last as well as by other causes of wrong ascent. Chapter twenty. When they are at work in the three great provinces of the intellectual world. Chapter twenty one. Concerned respectively with one things as knowable, physical, two actions as they depend on us in order to happiness, practical and three methods for interpreting the signs of what is and of what ought to be that are presented in our ideas and words. Logica. End of section zero. One. Our knowledge, conversant about our ideas only. Since the mind and all its thoughts and reasonings have no other immediate object but its own ideas, which it alone does or can contemplate, it is evident that our knowledge is only conversant about them. Two. Knowledge is the perception of the agreement or disagreement of two ideas. Knowledge then seems to me to be nothing but the perception of the connection of an agreement or disagreement and repugnancy of any of our ideas. In this alone it consists. Where this perception is, there is knowledge, and where it is not there though we may fancy guess or believe, yet we always come short of knowledge. For when we know that white is not black, what do we else but perceive that these two ideas do not agree? When we possess ourselves with the utmost security of the demonstration that the three angles of a triangle are equal to two right ones, what do we more but perceive that equality to two right ones does necessarily agree to and is inseparable from the three angles of a triangle? Three. This agreement or disagreement may be any of four sorts, but to understand a little more distinctly where in this agreement or disagreement consists, I think we may reduce it all to these four sorts. One. Identity or diversity. Two. Relation. Three. Coexistence or necessary connection. Four. Real existence. Four. First of identity or diversity in ideas. First as to the first sort of agreement or disagreement namely identity or diversity. It is the first act of the mind when it has any sentiments or ideas at all to perceive its ideas and so far as it perceives them to know each what it is and thereby also to perceive their difference and that one is not another. This is so absolutely necessary that without it there could be no knowledge, no reasoning, no imagination, no distinct thoughts at all. By this the mind clearly and infallibly perceives each idea to agree with itself and to be what it is and all distinct ideas to disagree, that is, the one not to be the other and this it does without pains, labor or deduction, but at first view by its natural power of perception and distinction. And though men of art have reduced this into those general rules, what is, is and it is impossible for the same thing to be and not to be for ready application in all cases were in there may be occasion to reflect on it. Yet it is certain that the first exercise of this faculty is about particular ideas. A man infallibly knows as soon as ever he has them in his mind that the ideas he calls white and round are the very ideas they are and that they are not other ideas which he calls red or square. Nor can any maxim or proposition in the world make him know it clear or sure than he did before and without any such general rule. This then is the first agreement or disagreement which the mind perceives in its ideas, which it always perceives at first sight and if there ever happen any doubt about it, it will always be found to be about the names and not the ideas themselves whose identity and diversity will always be perceived as soon and clearly as the ideas themselves are, nor can it possibly be otherwise. Five. Secondly of abstract relations between ideas. Secondly, the next sort of agreement or disagreement the mind perceives in any of its ideas may I think be called relative and it is nothing but the perception of the relation between any two ideas of what kind so ever, whether substances, modes or any other. For since all distinct ideas must eternally be known not to be the same and so be universally and constantly denied one of another, there could be no room for any positive knowledge at all if we could not perceive any relation between our ideas and find out the agreement or disagreement that they have with another in several ways the mind takes of comparing them. Six. Thirdly of their necessary coexistence in substances. Thirdly the third sort of agreement or disagreement to be found in our ideas which the perception of the mind is employed about is coexistence or non coexistence in the same subject and this belongs particularly to substances. Thus when we pronounce concerning gold that it is fixed our knowledge of this truth amounts to no more than this that fixedness or a power to remain in the fire unconsumed is an idea that always accompanies and is joined with that particular sort of yellowness, hate, fusibility, malleableness and salubility in aqua regia which makes our complex idea signified by the word gold. Seven. Fourthly of real existence agreeing to any idea. Fourthly the fourth and last sort is that of actual real existence agreeing to any idea. Within these four sorts of agreement or disagreement is I suppose contained all the knowledge we have or are capable of. For all the inquiries we can make concerning any of our ideas all that we know or can affirm concerning any of them is that it is or is not the same with some other that it does or does not always coexist with some other idea in the same subject, that it has this or that relation with some other idea or that it has a real existence without the mind. Thus blue is not yellow is of identity. Two triangles upon equal bases between two parallels are equal is of relation. Iron is susceptible of magnetical impressions is of coexistence. God is, is of real existence. Though identity and coexistence are truly nothing but relations yet they are such peculiar ways of agreement or disagreement of our ideas that they deserve well to be considered as distinct heads and not under relation in general since they are so different grounds of affirmation and negation as will easily appear to anyone who will but reflect on what is said in several places of this essay. I should now proceed to examine the several degrees of our knowledge but that it is necessary first to consider the different acceptations of the word knowledge. Eight, knowledge is either actual or habitual. There are several ways wherein the mind is possessed of truth each of which is called knowledge. One, there is actual knowledge which is the present view the mind has of the agreement or disagreement of any of its ideas or of the relation they have to one another. A man is said to know any proposition which having been once laid before his thoughts he evidently perceived the agreement or disagreement of the ideas whereof it consists and so lodged it in his memory that whenever that proposition comes again to be reflected on he without doubt or hesitation embraces the right side a sense to and is certain of the truth of it. This I think one may call habitual knowledge and thus a man may be said to know all those truths which are lodged in his memory by a foregoing clear and full perception whereof the mind is assured past doubt as often as it has occasion to reflect on them. For our finite understandings being able to think clearly and distinctly but on one thing at once if men had no knowledge of any more than what they actually thought on they would all be very ignorant and he that knew most would know but one truth that being all he was able to think on at one time. Nine. Habitual knowledges of two degrees. Of habitual knowledge there are also vulgarly speaking two degrees. First the one is of such truths laid up in the memory as whenever they occur to the mind it actually perceives the relation is between those ideas and this is in all those truths whereof we have an intuitive knowledge where the ideas themselves by an immediate view discover their agreement or disagreement one with another. Secondly the other is of such truths whereof the mind having been convinced it retains the memory of the conviction without the proofs thus a man that remember certainly that he once perceived the demonstration that the three angles of a triangle are equal to two right ones is certain that he knows it because he cannot doubt the truth of it. In his adherence to a truth where the demonstration by which it was at first known is forgot though a man may be thought rather to believe his memory than really to know and this way of entertaining a truth seemed formerly to me like something between opinion and knowledge a sort of assurance which exceeds bare belief for that relies on the testimony of another yet upon a due examination I find it comes not short of perfect certainty and is in effect true knowledge. That which is apt to mislead our first thoughts into a mistake in this matter is that the agreement or disagreement of the ideas in this case is not perceived as it was at first by an actual view of all the intermediate ideas whereby the agreement or disagreement of those in the proposition was at first perceived but by other intermediate ideas that show the agreement or disagreement of the ideas contained in the proposition whose certainty we remember. For example in this proposition that the three angles of a triangle are equal to two right ones one who is seen and clearly perceived the demonstration of this truth knows it to be true when that demonstration is gone out of his mind so that at present it is not actually in view and possibly cannot be recollected but he knows it in a different way from what he did before the agreement of the two ideas joined in that proposition is perceived but it is by the intervention of other ideas than those which at first produced this perception he remembers that is he knows for remembrance is but the reviving of some past knowledge that he was once certain of the truth of this proposition that the three angles of a triangle are equal to two right ones. The immutability of the same relations between the same immutable things is now the idea that shows him that if the three angles of a triangle were once equal to two right ones they will always be equal to two right ones and hence he comes to be certain that what was once true in the case is always true. What ideas once agreed will always agree and consequently what he once knew to be true he will always know to be true as long as he can remember that he once knew it. Upon this ground it is that particular demonstrations and mathematics afford general knowledge. If then the perception that the same ideas will eternally have the same habits and relations be not a sufficient ground of knowledge there could be no knowledge of general propositions in mathematics. For no mathematical demonstration would be any more than particular and when a man had demonstrated any proposition concerning one angle or a circle his knowledge would not reach beyond that particular diagram. If he would extend it further he must renew his demonstration in another instance before he could know it to be true in another like triangle and so on. By which means one could never come to the knowledge of any general propositions. Nobody I think can deny that Mr. Newton certainly knows any proposition that he now at any time reason his book to be true though he has not in actual view that admirable chain of intermediate ideas whereby he at first discovered it to be true. Such a memory as that able to retain such a train of particulars may be well thought beyond the reach of different faculties when the very discovery, perception and laying together that wonderful connection of ideas is found to surpass most readers comprehension. But yet it is evident the author himself knows the proposition to be true remembering he once saw the connection of those ideas as certainly as he knows such a man wounded another remembering that he saw him run him through. But because the memory is not always so clear as actual perception and does in all men more or less decay in length of time this amongst other differences is one which shows that demonstrative knowledge is much more imperfect than intuitive as we shall see in the following chapter. End of section one. Section two of an essay concerning human understanding by John Locke. Book four of knowledge and probability. This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer please visit LibriVox.org recording by Jennifer Henry. Chapter two of the degrees of our knowledge. One of the degrees or differences in clearness of our knowledge. One intuitive. All our knowledge consisting as I have said in the view the mind has of its own ideas which is the utmost light and greatest certainty we with our faculties and in our way of knowledge are capable of it may not be amiss to consider a little the degrees of its evidence. The different clearness of our knowledge seems to me to lie in the different way of perception the mind has of the agreement or disagreement of any of its ideas for if we will reflect on our own ways of thinking we will find that sometimes the mind perceives the agreement or disagreement of two ideas immediately by themselves without the intervention of any other and this I think we may call intuitive knowledge. For in this the mind is at no pains of proving or examining but perceives the truth as the eye doth light only by being directed towards it thus the mind perceives that white is not black that a circle is not a triangle that three are more than two and equal to one and two such kinds of truths the mind perceives at the first sight of the ideas together by bear intuition without the intervention of any other idea and this kind of knowledge is the clearest and most certain that human frailty is capable of this part of knowledge is irresistible and like bright sunshine forces itself immediately to be perceived as soon as ever the mind turns its view that way and leaves no room for hesitation doubt or examination but the mind is presently filled with the clear light of it it is on this intuition that depends all the certainty and evidence of all our knowledge which certainty everyone finds to be so great that he cannot imagine and therefore not require a greater for a man cannot conceive himself capable of a greater certainty than to know that any idea in his mind is such as he perceives it to be and the two ideas wherein he perceives a difference are different and not precisely the same he that demands a greater certainty than this demands he knows not what and shows only that he has a mind to be a skeptic without being able to be so certainty depends so wholly on this intuition that in the next degree of knowledge which I call demonstrative this intuition is necessary in all the connections of the intermediate ideas without which we cannot attain knowledge and certainty to to demonstrative the next degree of knowledge is where the mind perceives the agreement or disagreement of any ideas but not immediately though wherever the mind perceives the agreement or disagreement of any of its ideas there be certain knowledge yet it does not always happen that the mind sees that agreement or disagreement which there is between them even where it is discoverable and in that case remains in ignorance and at most gets no further than a probable conjecture the reason why the mind cannot always perceive presently the agreement or disagreement of two ideas is because those ideas concerning whose agreement or disagreement the inquiry has made cannot by the mind be so put together as to show it in this case then when the mind cannot so bring its ideas together as by their immediate comparison and as it were juxtaposition or application one to another to perceive their agreement or disagreement it is feigned by the intervention of other ideas one or more as it happens to discover the agreement or disagreement which it searches and this is that which we call reasoning thus the mind being willing to know the agreement or disagreement in bigness between the three angles of a triangle and two right ones cannot by an immediate view and comparing them do it because the three angles of a triangle cannot be brought at once and be compared with any other one or two angles and so of this the mind has no immediate no intuitive knowledge in this case the mind is feigned to find out some other angles to which the three angles of a triangle have an equality and finding those equal to two right ones comes to know their equality to two right ones three demonstration depends on clearly perceived proofs those intervening ideas which serve to show the agreement of any two others are called proofs and where the agreement and disagreement is by this means plainly and clearly perceived it is called demonstration it being shown to the understanding and the mind made to see that it is so a quickness in the mind to find out these intermediate ideas that shall discover the agreement or disagreement of any other and to apply them right is I suppose that which is called sagacity for as certain but not so easy and ready as intuitive knowledge this knowledge by intervening proofs though it be certain yet the evidence of it is not altogether so clear and bright nor the ascent so ready as in intuitive knowledge for though in demonstration the mind does at last perceive the agreement or disagreement of the ideas it considers yet it is not without pains and attention there must be more than one transient view to find it a steady application and pursuit are required to this discovery and there must be a progression by steps and degrees before the mind can in this way arrive at certainty and come to perceive the agreement or repugnancy between two ideas that need proofs and the use of reason to show it five the demonstrated conclusion not without doubt precedent to the demonstration another difference between intuitive and demonstrative knowledge is that though in the latter all doubt be removed when by the intervention of the intermediate ideas the agreement or disagreement is perceived yet before the demonstration there was a doubt which in intuitive knowledge cannot happen to the mind that has its faculty of perception left to a degree capable of distinct ideas more than it can be a doubt to the eye that can distinctly see white and black whether this ink and this paper be all of a color if there be sight in the eyes it will at first glimpse without hesitation perceive the words printed on this paper different from the color of the paper and so if the mind have the faculty of distinct perception it will perceive the agreement or disagreement of those ideas that produce intuitive knowledge if the eyes have lost the faculty of seeing or the mind of perceiving we in vain inquire after the quickness of sight in one or clearness of perception in the other six not so clear as intuitive knowledge it is true the perception produced by demonstration is also very clear yet it is often with a great abatement of that evident luster and full assurance that always accompany that which I call intuitive like a face reflected by several mirrors one to another where as long as it retains the similitude and agreement with the object it produces a knowledge but it is still in every successive reflection with a lessening of that perfect clearness and distinctness which is in the first till at last after many removes it has a great mixture of dimness and is not at first sight so knowable especially to weak eyes thus it is with knowledge made out by a long train of proof seven each step in demonstrated knowledge must have intuitive evidence now in every step reason makes in demonstrative knowledge there is an intuitive knowledge of that agreement or disagreement it seeks with the next intermediate idea which it uses as a proof for if it were not so that yet would need a proof since without the perception of such agreement or disagreement there is no knowledge produced if it be perceived by itself it is intuitive knowledge if it cannot be perceived by itself there is need of some intervening idea as a common measure to show their agreement or disagreement by which it is playing that every step in reasoning that produces knowledge has intuitive certainty which when the mind perceives there is no more required but to remember it to make the agreement or disagreement of the ideas concerning which we inquire visible and certain so that to make anything a demonstration it is necessary to perceive the immediate agreement of the intervening ideas agreement or disagreement of the two ideas under examination where of the one is always the first and the other the last in the account is found this intuitive perception of the agreement or disagreement of the intermediate ideas in each step and progression of the demonstration must also be carried exactly in the mind and a man must be sure that no part is left out which because in long deductions and the use of many proofs the memory does not always so readily and exactly retain therefore it comes to pass that this is more imperfect than intuitive knowledge and men embrace often falsehood for demonstrations eight hence the mistake ex precognitus et preconchesis the necessity of this intuitive knowledge in each step of scientific or demonstrative reasoning gave occasion I imagine to that mistaken axiom that all reasoning was ex precognitus et preconchesis which how far it is a mistake I shall have occasion to show more at large when I come to consider propositions and particularly those propositions which are called maxims and to show that it is by a mistake that they are supposed to be the foundations of all our knowledge and reasonings nine demonstration not limited to ideas of mathematical quantity it has been generally taken for granted that mathematics alone are capable of demonstrative certainty but to have such an agreement or disagreement as may intuitively be perceived being as I imagine not the privilege of the ideas of number extension and figure alone it may possibly be the want of due method and application in us and not of sufficient evidence in things that demonstration has been thought to have so little to do in other parts of knowledge and been scarce so much as aimed at by any but mathematicians for whatever ideas we have where in the mind can perceive the immediate agreement or disagreement that is between them there the mind is capable of intuitive knowledge and where it can perceive the agreement or disagreement of any two ideas by an intuitive perception of the agreement or disagreement they have with any intermediate ideas there the mind is capable of demonstration which is not limited to ideas of extension figure number and their modes ten why it has been thought to be so limited the reason why it has been generally sought for and supposed to be only in those I imagine has been not only the general usefulness of those sciences but because in comparing their equality or excess the modes of numbers have every the least difference very clear and perceivable and though in extension every the least excess is not perceptible yet the mind has found out ways to examine and discover demonstratively the just equality of two angles or extensions or figures and both these i.e. numbers and figures can be set down by visible and lasting marks where in the ideas under consideration are perfectly determined which for the most part they are not where they are marked only by names and words eleven modes of qualities not demonstrable like modes of quantity but in other simple ideas whose modes and differences are made and counted by degrees and not quantity we have not so nice and accurate a distinction of their differences as to perceive or find ways to measure their just equality or the least differences for those other simple ideas or appearances of sensations produced in us by the size, figure number and motion of minute corpuscles singly insensible their different degrees also depend on the variation of some or all those causes which since it cannot be observed by us in particles of matter where of each is too subtle to be perceived it is impossible for us to have exact measures of the different degrees of these simple ideas for supposing the sensation or idea we name whiteness be produced in us by a certain number of globules which having a verticity about their own centers strike upon the retina of the eye with a certain degree of rotation as well as progressive swiftness it will hence easily follow that the more the superficial parts of any body are so ordered as to reflect the greater number of globules of light and to give them the proper rotation which is fit to produce the sensation of white in us the more white will that body appear that from an equal space sends to the retina the greater number of such corpuscles with that particular sort of motion I do not say that the nature of light consists in very small round globules nor of whiteness in such a texture of parts as gives a certain rotation to these globules when it reflects them for I am not now treating physicality of light or colors but this I think I may say that I cannot and it would be glad anyone would make intelligible that he did conceive how bodies without us can anyways affect our senses but by the immediate contact of the sensible bodies themselves as in tasting and feeling or the impulse of some sensible particles coming from them as in seeing hearing and smelling by the different impulse of which parts caused by their different size figure and motion the variety of sensations is produced in us 12 particles of light and simple ideas of color whether then they be globules or no or whether they have a verticity about their own centers that produces the idea of whiteness in us this is certain that the more particles of light are reflected from a body fitted to give them that peculiar motion which produces the sensation of whiteness in us and possibly to the quicker that peculiar motion is the whiter does the body appear from which the greatest number are reflected as is evident in the same piece of paper put in the sunbeams in the shade and in a dark hole in each of which it will produce in us the idea of whiteness in far different degrees 13 the secondary qualities of things not discovered by demonstration not knowing therefore what number of particles motion of them is fit to produce any precise degree of whiteness we cannot demonstrate the certain equality of any two degrees of whiteness because we have no certain standard to measure them by nor means to distinguish every the least real difference the only help we have being from our senses which in this point fail us but where the difference is so great as to produce in the mind clearly distinct ideas whose differences can be perfectly retained there these ideas or colors as we see in different kinds as blue and red are as capable of demonstration as ideas of number and extension what I have here said of whiteness and colors I think holds true in all secondary qualities and their modes 14 3 sensitive knowledge of the particular existence of finite beings without us these two these intuition and demonstration are the degrees of our knowledge whatever comes short of one of these with what assurance so ever embraced is but faith or opinion but not knowledge at least in all general truths there is indeed another perception of the mind employed about the particular existence of finite beings without us which going beyond bare probability and yet not reaching perfectly to either of the foregoing degrees of certainty passes under the name of knowledge there can be nothing more certain than that the idea we receive from an external object is in our minds this is intuitive knowledge but whether there be anything more than barely that idea in our minds whether we can then certainly infer the existence of anything without us which corresponds to that idea is that where of some men think there may be a question made because men may have such ideas in their minds when no such thing exists no such object affects their senses but yet here I think we are provided with an evidence that puts us past doubting for I ask anyone whether he be not invincibly conscious to himself of a different perception when he looks on the sun by day and thinks on it by night when he actually tastes warmwood or smells a rose or only thinks on that savor or odor we as plainly find the difference there is between any idea revived in our minds by our own memory actually coming into our minds by our senses as we do between any two distinct ideas if anyone say a dream may do the same thing and all these ideas may be produced in us without any external objects he may be pleased to dream that I make him this answer one that it is no great matter whether I remove his scruple or no where all is but dream reasoning and arguments are of no truth and knowledge nothing too that I believe he will allow a very manifest difference between dreaming of being in the fire and being actually in it but yet if he be resolved to appear so skeptical as to maintain that what I call being actually in the fire is nothing but a dream and that we cannot thereby certainly know that any such thing as fire actually exists without us I answer that we certainly finding that pleasure or pain follows upon the application of certain objects to us whose existence we perceive or dream that we perceive by our senses this certainty is as great as our happiness or misery beyond which we have no concernment to know or to be so that I think we may add to the two former sorts of knowledge this also of the existence of particular external objects by that perception and consciousness we have of the actual entrance of ideas from them and allow these three degrees of knowledge these intuitive, demonstrative and sensitive in each of which there are different degrees and ways of evidence and certainty fifteen our knowledge not always clear where the ideas that enter into it are clear but since our knowledge is founded on and employed about our ideas only will it not follow from thence that it is conformable to our ideas and that where our ideas are clear and distinct or obscure and confused our knowledge will be so too to which I answer no for our knowledge consisting in the perception of the agreement or disagreement of any two ideas it's clearness or obscurity consists in the clearness or obscurity of that perception and not in the clearness or obscurity of the ideas themselves VG a man that has as clear ideas of the angles of a triangle and of a quality to two right ones as any mathematician in the world may yet have but a very obscure perception of their agreement and so have but a very obscure knowledge of it but ideas which by reason of their obscurity or otherwise are confused cannot produce any clear or distinct knowledge because as far as any ideas are confused so far the mind cannot perceive clearly whether they agree or disagree to express the same thing in a way less apt to be misunderstood he that hath not determined ideas to the words he uses cannot make propositions of them of whose truth he can be certain End of Section 2 Recording by Jennifer Henry Section 3 of an essay concerning human understanding by John Locke Book 4 of Knowledge and Probability This is a LibriVox recording All LibriVox recordings are in the public domain. For more information or to volunteer please visit LibriVox.org Recording by Matthew Bennett Chapter 3 of the extent of human knowledge 1. Extent of our knowledge Knowledge, as has been said lying in the perception of the agreement or disagreement of any of our ideas it follows from hence that First, it extends no further than we have ideas First, we can have knowledge no further than we have ideas 2. Secondly, it extends no further than we can perceive their agreement or disagreement Secondly, that we can have no knowledge further than we can have perception of that agreement or disagreement which perception being one, either by intuition comparing any two ideas or two, by reason examining the agreement or disagreement of two ideas by the intervention of some others or three, by sensation perceiving the existence of particular things Hence, it also follows 3. Thirdly, intuitive knowledge extends itself not to all the relation of all our ideas Thirdly, that we cannot have an intuitive knowledge that shall do all our ideas and all that we would know about them because we cannot examine and perceive all the relations they have one to another by juxtaposition or an immediate comparison one with another Thus, having the ideas of an obtuse and an acute-angled triangle both drawn from equal bases and between parallels I can, by intuitive knowledge perceive the one not to be the other that they know whether they be equal or no because their agreement or disagreement in equality can never be perceived by an immediate comparing them The difference of figure makes their parts incapable of an exact immediate application and therefore there is need of some intervening qualities to measure them by which is demonstration or rational knowledge 4. Fourthly, nor does demonstrative knowledge Fourthly, it follows also from what is above observed that our rational knowledge cannot reach to the whole extent of our ideas because between two different ideas we would examine we cannot always find such mediums as we can connect to one another with an intuitive knowledge in all the parts of the deduction and wherever that fails we come short of knowledge in demonstration 5. Fifthly, sensitive knowledge reaching no further than the existence of things actually present to our senses is yet much narrower than either of the former 6. Sixthly, our knowledge therefore narrower than our ideas 6. Sixthly, from all which it is evident that the extent of our knowledge comes not only short of the reality of things but even of the extent of our own ideas though our knowledge be limited to our ideas and cannot exceed them either in extent or perfection and though these be very narrow bounds in respect of the extent of all being and far short of what we may justly imagine to be in some even created understandings not tied down to the dull and narrow information that is to be received from some few and not very acute ways of perception such as are our senses yet it would be well with us if our knowledge were but as large as our ideas and there were not many doubts and inquiries concerning the ideas we have, whereof we are not nor I believe ever shall be in this world resolved nevertheless I do not question but that human knowledge under the present circumstances of our beings and constitutions may be carried much further than it has hitherto been if men would sincerely employ all that industry and labor of thought in improving the means of discovering truth which they do for the coloring or support of falsehood to maintain a system, interest, or party they are once engaged in but yet after all I think I may without injury to human perfection be confident that our knowledge would never reach to all we might desire to know concerning those ideas we have nor be able to surmount all the difficulties and resolve all the questions that might arise concerning any of them we have the ideas of a square a circle and equality and yet perhaps shall never be able to find a circle equal to a square and certainly know that it is so we have the ideas of matter and thinking but possibly shall never be able to know whether any mere material being thinks or know it being impossible for us by the contemplation of our own ideas without revelation to discover where omnipotency has not given to some systems of matter fitly disposed a power to perceive and think or else joined and fixed to matter so disposed a thinking immaterial substance it being in respect of our notions not much more remote from our comprehension to conceive that God can, if he pleases super add to matter a faculty of thinking then he should super add to it another substance with a faculty of thinking since we know not wherein thinking consists nor to what sort of substances the Almighty has been pleased to give that power which cannot be in any created being but merely by the good pleasure and bounty of the Creator for I see no contradiction in it that the first eternal thinking being or omnipotent spirit should be pleased give to certain systems of created senseless matter put together as he thinks fit some degrees of sense perception and thought though as I think I have proved it is no less than a contradiction to suppose matter which is evidently in its own nature void of sense and thought should be that eternal first thinking being what certainty of knowledge can anyone have that some perceptions such as VG pleasure and pain should not be in some bodies themselves after a certain manner modified and moved as well as that they should be in an immaterial substance upon the motion of the parts of the body body as far as we can conceive being able only to strike and affect body and motion according to the utmost reach of our ideas being able to produce nothing but motion so that when we allow it to produce pleasure or pain or the idea of a color or sound we are feigned to quit our reason go beyond our ideas and attribute it wholly to the good pleasure of our maker for since we must allow he has annexed defects to motion which we can no way conceive motion able to produce what reason have we to conclude that he could not order them as well to be produced in a subject we cannot conceive capable of them as well in a subject we cannot conceive the motion of matter can anyway operate upon I say not this that I would anyway lessen the belief of the soul's immateriality I am not here speaking of probability but knowledge and I think not only that it becomes the modesty of philosophy not to pronounce magisterially where we want that evidence that can produce knowledge but also that it is of use to us to discern how knowledge does reach for the state we are at present in not being that of vision we must in many things content ourselves with faith and probability and in the present question about the immateriality of the soul if our faculties cannot arrive at demonstrative certainty we need not think it strange all the great ends of morality and religion are well enough secured without philosophical proofs of the soul's immateriality it is evident that he who made us at the beginning to subsist here sensible intelligent beings and for several years continued us in such a state can and will restore us to the like state of sensibility in another world and make us capable there to receive the retribution he has designed to men according to their doings in this life and therefore it is not of such mighty necessity to determine one way or the other as some of the immateriality of the soul have been forward to make the world believe who either on one side indulging too much their thoughts immersed all together in matter can allow no existence to what is not material or who on the other side finding not cogitation within the natural powers of matter examined over and over again by the utmost intention of mind have the confidence to conclude that omnipotency itself cannot give perception and thought to a substance which has the modification of solidity he that considers how hardly sensation is in our thoughts reconcilable to extended matter or existence to anything that has no extension at all will confess that he is very far from certainly knowing what his soul is it is a point which seems to me to be put out of the reach of our knowledge and he who will give himself leave to consider freely and look into the dark and intricate part of each hypothesis will scarce find his reason able to determine him fixedly for or against the soul's materiality since on which side so ever he views it either as an unextended substance or as a thinking extended matter the difficulty to conceive either will whilst either alone is in his thoughts still drive him to the contrary an unfair way which some men take with themselves who because of the inconceivableness of something they find in one throw themselves violently into the contrary hypothesis though altogether as unintelligible to an unbiased understanding this serves not only to show the weakness and the scantiness of our knowledge but the insignificant triumph of such sort of arguments which drawn from our own views satisfy us that we can find no certainty on one side of the question but do not at all thereby help us to truth by running into the opposite opinion which on examination will be found clogged with equal difficulties for what safety what advantage to anyone is it for the avoiding the seeming absurdities and to him uncermountable rubs he meets with in one opinion to take refuge in the contrary which is built on something altogether as inexplicable and is far remote from his comprehension it is past controversy that we have in us something that thinks our very doubts about what it is confirm the certainty of its being though we must content ourselves in the ignorance of what kind of being it is and it is in vain to go out to be skeptical in this as it is unreasonable in most other cases to be positive against the being of anything because we cannot comprehend its nature for I would feign know what substance exists that has not something in it which manifestly baffles our understandings other spirits who see and know the nature and inward constitution of things how much must they exceed us in knowledge to which if we had larger comprehension which enables them at one glance to see the connection and agreement of very many ideas and readily supplies to them the intermediate proofs which we by single and slow steps and long pouring in the dark hardly at last find out and are often ready to forget one before we have hunted out another we may guess at some part of the happiness of superior ranks of spirits who have a quicker and more penetrating sight as well as a larger field of knowledge but to return to the argument in hand our knowledge I say limited to the paucity and imperfections of the ideas we have and which we employ it about but even comes short of that too but how far it reaches let us now inquire seven how far our knowledge reaches the affirmations or negations we make concerning the ideas we have may as I have before intimated in general be reduced to these four sorts is identity coexistence relation and real existence I shall examine how far our knowledge extends in each of these eight firstly our knowledge of identity and diversity in ideas extends as far as our ideas themselves first as to identity and diversity in this way of agreement or disagreement of our ideas our intuitive knowledge is as far extended as our ideas themselves and there can be no idea in the mind which it does not presently by an intuitive knowledge perceived to be what it is and to be different from any other nine secondly of their coexistence extends only a very little way secondly as to the second sort which is the agreement or disagreement of our ideas in coexistence in this our knowledge is very short though in this consists the greatest and most material part of our knowledge concerning substances for our ideas of the species of substances being as I have showed nothing but certain collections of simple ideas united in one subject and so coexisting together V.G. our idea of flame is a body hot luminous and moving upward of gold a body heavy to a certain degree yellow malleable and fusible for these or some such complex ideas as these in men's minds do these two names of the different substances flame and gold stand for when we would know anything further concerning these or any other sort of substances what do we inquire but what other qualities or powers these substances have or have not which is nothing else but to know what other simple ideas do or do not coexist with those that make up complex idea 10. because the connection between simple ideas and substances is for the most part unknown this how weighty and considerable a part so ever of human science is yet very narrow and scarce any at all the reason whereof is that the simple ideas whereof our complex ideas of substances are made up are for the most part such as carry with them our own nature no visible necessary connection or inconsistency with any other simple ideas whose coexistence with them we would inform ourselves about 11. especially of the secondary qualities of bodies the ideas that our complex ones of substances are made up of and about which our knowledge concerning substances is most employed are those of their secondary qualities all as has been shown upon the primary qualities of their minute and insensible parts or if not upon them upon something yet more remote from our comprehension it is impossible we should know which have a necessary union or inconsistency one with another for not knowing the root they spring from not knowing what size, figure and texture of parts they are on which depend which make our complex idea of gold it is impossible we should know what other qualities result from or are incompatible with the same constitution of the insensible parts of gold and so consequently must always coexist with that complex idea we have of it or else are inconsistent with it 12. because necessary connection between any secondary and the primary qualities is undiscoverable by us besides this ignorance of the primary qualities of the insensible parts of bodies on which depend all their secondary qualities there is yet another and more incurable part of ignorance which sets us more remote from a certain knowledge of the coexistence or inco-existence if I may so say of different ideas in the same subject and that is that there is no discoverable connection between any secondary quality and those primary qualities which it depends on 13. we have no perfect knowledge of their primary qualities that the size, figure and motion of one body should cause a change in the size, figure and motion of another body is not beyond our conception the separation of the parts of one body upon the intrusion of another and a change from rest to motion upon impulse these and the like seem to have some connection one with another and if we knew these primary qualities of bodies we might have reason to hope we might be able to know a great deal more of these operations of them one upon another but our minds not being able to discover any connection betwixt these primary qualities of bodies and the sensations that are produced in us by them we can never be able to establish certain and undoubted rules of sequence or coexistence of any secondary qualities though we could discover the size, figure or motion of those invisible parts which immediately produce them we are so far from knowing what figure, size or motion of parts produce a yellow color a sweet taste or a sharp sound that we can by no means conceive how any size, figure or motion of any particles can possibly produce in us the idea of any color, taste or sound whatsoever there is no conceivable connection between the one and the other 14 and seek in vain for certain and universal knowledge of unperceived qualities in substances in vain therefore shall we endeavor to discover by our ideas the only true way of certain and universal knowledge what other ideas are to be found constantly joined with that of our complex idea of any substance since we neither know the real constitution of the minute parts on which their qualities do depend nor did we know them could we discover any necessary connection between them and any of the secondary qualities which is necessary to be done before we can certainly know their necessary coexistence so that let our complex idea of any species of substances be what it will we can hardly from the simple ideas contained in it certainly determine the necessary coexistence of any other quality whatsoever our knowledge in all these inquiries reaches very little further than our experience indeed some few of the primary qualities have a necessary dependence and visible connection one with another as figure necessarily supposes extension receiving or communicating motion impulse supposes solidity but through these and perhaps some others of our ideas have yet there are so few of them that have a visible connection one with another that we can by intuition or demonstration discover the coexistence of very few of the qualities that are to be found united in substances and we are left only to the assistance of our senses to make known to us what qualities they contain for all of the qualities that are co-existent in any subject without this dependence and evident connection of their ideas one with another we cannot know certainly any two to coexist any further than experience by our senses informs us thus though we see the yellow color and upon trial find the weight malleableness fusibility and fixedness that are united in a piece of gold yet because no one of these ideas has any evident dependence or necessary connection with the other we cannot certainly know that where any four of these are the fifth will be there also how highly probable so ever it may be because the highest probability amounts not to certainty without which there can be no true knowledge for this coexistence can be no further known than it is perceived and it cannot be perceived but either in particular subjects by the observation of our senses or general by the necessary connection of the ideas themselves fifteen of repugnancy to coexist our knowledge is larger as to the incompatibility or repugnancy to coexistence we may know that any subject may have of each sort of primary qualities but one particular at once vg each particular extension figure number of parts motion excludes all other of each kind the like also is certain of all sensible ideas peculiar to each sense for whatever of each kind is present in any subject excludes all other of that sort vg no one subject can have two smells or two colors at the same time to this perhaps will be said has not an opal or the infusion of lignum nephriticum two colors at the same time to which I answer that these bodies to eyes differently placed may at the same time afford different colors but I take liberty also to say that to eyes differently placed it is different parts of the object that reflect the particles of light and therefore it is not the same part of the object and so not the very same subject which at the same time appears both yellow and azure for it is as impossible that the very same particle of any body should at the same time differently modify or reflect the rays of light as that it should have two different figures and textures at the same time 16 our knowledge of the coexistence of power in bodies extends but a very little way but as to the powers of substances to change the sensible qualities of other bodies which make a great part of our inquiries about them and is no considerable branch of our knowledge I doubt as to these whether our knowledge reaches much further than our experience or whether we can come to the discovery of most of these powers and be certain that they are in any subject by the connection with any of those ideas which to us makes its essence because the active and passive powers of bodies and their ways of operating consisting in a texture and motion of parts which we cannot by any means to discover it is but in very few cases we can be able to perceive their dependence on or repugnance to any of those ideas which make our complex one of that sort of things I have here instanced in the corpuscularian hypothesis as that which is thought to go furthest in an intelligible of those qualities of bodies and I fear the weakness of human understanding is scarce able to substitute another which will afford us better and clearer discovery of the necessary connection and coexistence of the powers which are to be observed united in several sorts of them this at least is certain that whichever hypothesis be clearest and truest for of that it is not my business to determine our knowledge concerning corporeal substances will be very little advanced by any of them till we are made to see what qualities and powers of bodies have a necessary connection or repugnancy one with another which in the present state of philosophy I think we know but to a very small degree and I doubt whether with those faculties we have we shall ever be able to carry our general knowledge I say not particular experience in this part much further experiences that which in this part we must depend on and it were to be wished that it were more improved we find the advantages some men's generous pains have this way brought to the stock of natural knowledge and if others especially the philosophers by fire who pretend to it had been so wary in their observations and sincere in their reports as those who call themselves philosophers ought to have been our acquaintance with the bodies here about us and our insight into their powers and operations had been yet much greater 17 of the powers that coexist in spirits yet narrower if we are at a loss in respect of the powers and operations of bodies I think it is easy to conclude we are much more in the dark in reference to spirits where we naturally have no ideas but what we draw from that of our own by reflecting on the operations of our own souls within us as far as they can come within our observation but how inconsiderable a rank the spirits that inhabit our bodies and possibly innumerable kinds of nobler beings and how far short they come of the endowments and perfections of cherubim and seraphim and infinite sorts of spirits above us is what by a transient hint in another place I have offered to my readers consideration 18 thirdly of relations between abstracted ideas it is not easy to say how far our knowledge extends secondly as to the third sort of our knowledge vis the agreement or disagreement of any of our ideas in any other relation this as it is the largest field of our knowledge so it is hard to determine how far it may extend because the advances that are made in this part of knowledge depending on our sagacity and finding intermediate ideas that may show the relations and habitudes of ideas whose coexistence is not considered it is a hard matter to tell when we are at an end of such discoveries and when reason has all the helps it is capable of for the finding of proofs or examining the agreement or disagreement of remote ideas they that are ignorant of algebra cannot imagine the wonders in this kind are to be done by it and what further improvements and helps advantageous to other parts of knowledge the sagacious mind of man may yet find out it is not easy to determine this at least I believe that the ideas of quantity are not those alone that are capable of demonstration and knowledge and that other and perhaps more useful parts of contemplation would afford us certainty if vices, passions, and domineering interest did not oppose or menace such endeavors morality capable of demonstration the idea of a supreme being infinite in power, goodness and wisdom whose workmanship we are and on whom we depend and the idea of ourselves as understanding rational creatures being such as are clear in us would I suppose if duly considered and pursued afford such foundations of our duty and rules of action as might place morality amongst the sciences capable of demonstration wherein I doubt not but from self-evident propositions and consequences as incontestable as those in mathematics the measures of right and wrong might be made out to anyone that will apply himself with the same indifference and attention to the one as he does to the other of these sciences the relation of other modes may certainly be perceived as well as those of number and extension and I cannot see why they should not also be capable of demonstration if due methods were thought on to examine or pursue their agreement or disagreement where there is no property there is no injustice is a proposition as certain as any demonstration in Euclid for the idea of property being a right to anything and the idea of which the name injustice is given being the invasion or violation of that right it is evident that these ideas being thus established and these names annexed to them I can as certainly know as true as that a triangle has three angles equal to two right ones again no government allows absolute liberty the idea of government being the establishment of society upon certain rules or laws which require conformity to them and the idea of absolute liberty being for anyone to do whatever he pleases I am as capable of being certain of the truth of this proposition as of any in the mathematics 19 two things have made moral ideas to be thought incapable of demonstration their unfitness for sensible representation and their complexities that which in this respect has given the advantage to the ideas of quantity and made them thought more capable of certainty and demonstration is first that they can be set down and represented by sensible marks which have a greater and nearer correspondence than any words or sounds whatsoever diagrams drawn on paper or copies of the ideas in the mind and not liable to the uncertainty that words carry in their signification an angle, circle, or square drawn in lines lies open to the view and cannot be mistaken it remains unchangeable and may at leisure be considered and examined and the demonstration be revised and all the parts of it may be gone over more than once without any danger of the least change in the ideas this cannot be thus done in moral ideas we have no sensible marks that resemble them whereby we can set them down we have nothing but words to express them by which though when written they remain the same yet the ideas they stand for may change in the same man and it is very seldom that they are not different in different persons similarly another thing that makes the greater difficulty in ethics is that moral ideas are commonly more complex than those of the figures ordinarily considered in mathematics from once these two inconveniences follow first that their names are of more uncertain signification the precise collection of simple ideas they stand for not being so easily agreed on and so the sign that is used for them in communication always and in thinking often does not steadily carry with it the same idea upon which the same disorder confusion and error follow as would if a man going to demonstrate something of an heptagon should in the diagram he took to do it leave out one of the angles or by oversight make the figure with one angle more than the name ordinarily imported or he intended it should when at first he thought of his demonstration often happens and is hardly avoidable in very complex moral ideas where the same name being retained one angle i.e. one simple idea is left out or put in the complex one still called by the same name more at one time than another secondly from the complexedness of these moral ideas their follow is another inconvenience vis that the mind cannot easily retain those precise combinations so exactly and perfectly as is necessary in the examination of the habitudes and correspondences agreements or disagreements of several of them one with another especially where it is to be judged of by long deductions and the intervention of several other complex ideas to show the agreement or disagreement of two remote ones the great help against this which mathematicians find in diagrams and figures which remain unalterable in their drafts is very apparent and the memory would often have great difficulty otherwise to retain them so exactly whilst the mind went over the parts of them step by step to examine their several correspondences and though in casting up a long sum either in addition multiplication or division every part be only a progression of the mind taking a view of its own ideas and considering their agreement or disagreement and the resolution be nothing but the result of the whole made up of such particulars whereof the mind has a clear perception yet without setting down the several parts by marks whose precise significations are known and by marks that last and remain in view when the memory had let them go it would be almost impossible to carry so many different ideas in the mind without confounding or letting slip some parts of the reckoning and thereby having all our reasonings about it useless in which case the ciphers or marks help not the mind at all to perceive the agreement of any two or more numbers their equalities or proportions that the mind has only by intuition of its own ideas of the numbers themselves but the numerical characters are helps to the memory to record and retain the several ideas about which the demonstration is made whereby a man may know far his intuitive knowledge in surveying several of the particulars has proceeded that so he may without confusion go on to what is yet unknown and at last have in one view before him the result of all his perceptions and reasonings 20 remedies of our difficulties in dealing demonstratively with moral ideas one part of these disadvantages and moral ideas which has made them to be thought not capable of demonstration may in a good measure be remedied by definitions setting down that collection of simple ideas which every term shall stand for and then using the terms steadily and constantly for that precise collection and what methods, algebra or something of that kind may hereafter suggest to remove the other difficulties it is not easy to foretell confident I am that if men would in the same method search after moral as they do mathematical truths they would find them have a stronger connection one with another and a more necessary consequence from our clear and distinct ideas and to come nearer perfect demonstration that is commonly imagined but much of this is not to be expected whilst the desire of esteem riches or power makes men espouse the well endowed opinions in fashion and then seek arguments either to make good their beauty or varnish over and cover their deformity nothing being so beautiful to the eye as truth is to the mind nothing so deformed and irreconcilable to the understanding as a lie for though many a man can with satisfaction enough own a no very handsome wife in his bosom yet who is bold enough openly to avow that he has espoused a falsehood and received into his breast so ugly a thing as a lie whilst the parties of men cram their tenants down all men's throats whom they can get into their power without permitting them to examine their truth or falsehood and will not let truth have fair play in the world nor men the liberty to search after it what improvements can be expected of this kind what greater light can be hoped for in the moral sciences the subject part of mankind in most places might instead thereof with the Egyptian bondage expect Egyptian darkness were not the candle of the Lord set up by himself in men's minds which it is impossible for the breath or power of man wholly to extinguish twenty one fourthly of the three real existences of which we have certain knowledge fourthly as to know the fourth sort of our knowledge is of the real actual existence of things we have an intuitive knowledge of our own existence and a demonstrative knowledge of the existence of a God of the existence of anything else we have no other but a sensitive knowledge which extends not beyond the objects present to our senses end of section three section four of an essay concerning human understanding by John Locke book four of knowledge and probability this is a LibriVox recording are in the public domain for more information or to volunteer please visit LibriVox.org recording by Matthew Bennett twenty two our ignorance great our knowledge being so narrow as I have shown it will perhaps give us some light into the present state of our minds if we look a little into the dark side and take a view of our ignorance which being infinitely larger than our knowledge may serve much to the quieting of disputes and improvement of useful knowledge if discovering how far we have clear and distinct ideas we can find our thoughts within the contemplation of those things that are within the reach of our understandings and launch not out into that abyss of darkness where we have not eyes to see nor faculties to perceive anything out of a presumption that nothing is beyond our comprehension but to be satisfied of the folly of such a conceit we need not go far he that knows anything knows this in the first place that he need not seek long for instances of his ignorance the meanest and most obvious things that come in our way have dark sides that the quickest sight cannot penetrate into the clearest and most enlarged understandings of thinking men find themselves puzzled and at a loss in every particle of matter we shall the less wonder to find it so when we consider the causes of our ignorance which from what has been said I suppose will be found to be these three first want of ideas it's causes secondly want of a discoverable connection between the ideas we have thirdly want of tracing and examining our ideas 23 first one cause of our ignorance want of ideas one want of simple ideas that other creatures in other parts of the universe may have first there are some things and those not a few that we are ignorant of for want of ideas first all the simple ideas we have are confined as I have shown to those we receive from corporeal objects by sensation and from the operations of our own minds as the objects of reflection but how much these few and narrow inlets are disproportionate to the vast whole extent of all beings will not be hard to persuade those who are not so foolish as to think their span the measure of all things what other simple ideas it is possible the creatures in other parts of the universe may have by the assistance of senses and faculties more or perfecter than we have or different from ours it is not just to determine but to say or think there are no such because we conceive nothing of them is no better an argument than if a blind man should be positive in it that there was no such thing as sight and colors because he had no manner of idea of any such thing nor could by any means frame to himself any notions about seeing the ignorance and darkness that is in us no more hinders nor confines the knowledge that is in others the blindness of a mole is an argument against the quick-sightedness of an eagle he that will consider the infinite power wisdom and goodness of the creator of all things will find reason to think it was not all laid out upon so inconsiderable, mean and impotent a creature as he will find man to be who in all probability is one of the lowest of all intellectual beings what faculties therefore other species of creatures have put into the nature and in most constitutions of things what ideas they may receive of them far different from ours we know not this we know and certainly find that we want several other views of them besides those we have to make discoveries of them more perfect and we may be convinced that the ideas we can attain to by our faculties are very disproportionate to things themselves when a positive, clear distinct one of substance itself which is the foundation of all the rest is concealed from us but one of ideas of this kind being a part as well as cause of our ignorance cannot be described only this I think I may confidently say of it that the intellectual and sensible world are in this perfectly alike that that part which we see of either of them holds no proportion with what we see not and whatsoever we can reach with our eyes or our thoughts of either of them is but a point almost nothing in comparison of the rest 24 want of simple ideas that men are capable of having but having not one because their remoteness or secondly another great cause of ignorance is the want of ideas we are capable of as the want of ideas which our faculties are not able to give us shuts us wholly from those views which it is reasonable to think other beings perfecter than we have of which we know nothing so the want of ideas I now speak of keeps us in ignorance of things we conceive capable of being known to us bulk figure and motion we have ideas of but though we are not without ideas of these primary qualities of bodies in general yet not knowing what is the particular bulk figure and motion of the greatest part of the universe we are ignorant of the several powers efficacies and ways of operation whereby the effects which we daily see are produced these are hid from us in some things by being too remote and in others by being too minute when we consider the vast distance of the known invisible parts of the world and the reasons we have to think that what lies within our can is but a small part of the universe we shall then discover a huge abyss of ignorance what are the particular fabrics of the great masses of matter which make up the whole stupendous frame of corporeal beings how far they are extended what is their motion and how continued or communicated and what influence they have one upon another are contemplations that at first glimpse our thoughts lose themselves in if we narrow our contemplations and confine the total canton I mean this system of our sun and the grosser masses of matter that visibly move about it what several sorts of vegetables animals and intellectual corporeal beings infinitely different from those of our little spot of earth may there probably be in the other planets to the knowledge of which even of their outward figures and parts we can no way attain whilst we are confined to this earth there being no natural means either by sensation or reflection to convey their certain ideas into our minds they are out of the reach of those inlets of all our knowledge and what sorts of furniture and inhabitants those mansions contain in them we cannot so much as guess much less have clear and distinct ideas of them twenty five two because of their minuteness if a great nay far the greatest part of the several ranks of bodies in the universe escape our notice by their remoteness there are others that are no less concealed from us by their minuteness these insensible corpuscles being the active parts of matter and the great instruments of nature on which depend not only all their secondary qualities but also most of their natural operations our want of precise distinct ideas of their primary qualities keeps us in an incurable ignorance of what we desire to know about them I doubt not but if we could discover the figure size texture and motion of the minute constituent parts of any two bodies we should know without trial several of their operations one upon another as we do now the properties of a square or a triangle did we know the mechanical affections of the particles of rhubarb hemlock opium and a man as a watchmaker does those of a watch whereby it performs its operations and of a file which by rubbing on them will alter the figure of any of the wheels we should be able to tell beforehand that rhubarb will purge hemlock kill and opium make a man sleep as well as a watchmaker can that a little piece of paper laid on the balance will keep the watch from going till it be removed or that some small part of it being rubbed by a file the machine would quite lose its motion and the watch go no more the dissolving of silver in aqua fortis and gold in aqua regia and not vice versa would be then perhaps no more difficult to know than it is to a smith to understand why the turning of one key will open a lock and not the turning of another but whilst we are destitute of senses acute enough to discover the minute particles of bodies and to give us ideas of their mechanical affections we must be content to be ignorant of their properties and ways of operation nor can we be assured about them any further than some few trials we make are able to reach whether they will succeed again another time we cannot be certain this hinders our certain knowledge of universal truths concerning natural bodies and our reason carries us herein very little beyond particular matter of fact 26 hence no science of bodies within our reach and therefore I am apt to doubt that how far so ever human industry may advance useful and experimental philosophy and physical things scientific will still be out of our reach because we want perfect and adequate ideas of those very bodies which are nearest to us and most under our command those which we have ranked into classes under names and we think ourselves best acquainted with we have but very imperfect and incomplete ideas of distinct ideas of the several sorts of bodies that fall under the examination of our senses perhaps we may have but adequate ideas I suspect we have not of anyone amongst them and though the former of these will serve us for common use and discourse yet whilst we want the latter we are not capable of scientific knowledge nor shall ever be able to cover general instructive unquestionable truths concerning them certainty and demonstration are things we must not in these matters pretend to by the color, figure, taste and smell and other sensible qualities we have as clear and distinct ideas of sage and hemlock as we have of a circle and triangle but having no ideas of the particular primary qualities of the minute parts of either of these plants nor of other bodies which we would apply them to we cannot tell what effects they will produce nor when we see those effects can we so much as guess much less know their manner of production thus having no ideas of the particular mechanical affections of the minute parts of bodies that are within our view and reach we are ignorant of their constitutions powers and operations and of bodies more remote we are yet more ignorant not knowing so much as their very outward shapes or the sensible and grosser parts of their constitutions twenty seven much less a science of unembodied spirits this at first will show us how disproportionate our knowledge is to the whole extent even of material beings to which if we add the consideration of that infinite number of spirits that may be and probably are which are yet more remote from our knowledge whereof we have no cognizance nor can frame to ourselves any distinct ideas of their several ranks and sorts we shall find this cause of ignorance concealed from us in an impenetrable obscurity almost the whole intellectual world a greater certainty and more beautiful world than the material for baiting some very few and those if I may so call them superficial ideas of spirit which by reflection we get of our knowledge and from thence the best we can collect of the father of all spirits the eternal independent author of them and us and all things we have no certain information so much as of the existence of other spirits but by revelation angels of all sorts are naturally beyond our discovery and all those intelligences whereof it is likely there are more orders than of corporeal substances are things whereof our natural tendencies give us no certain account at all that there are minds and thinking beings and other men as well as himself every man has a reason from their words and actions to be satisfied and the knowledge of his own mind cannot suffer a man that considers to be ignorant that there is a God but that there are degrees of spiritual beings between us and the great God who is there that by his own search and ability can come to know much less have we distinct ideas of their different natures conditions states powers and several constitutions wherein they agree or differ from one another and from us and therefore in what concerns their different species and properties we are in absolute ignorance twenty eight secondly another cause want of a discoverable connection between ideas we have what a small part of the substantial beings that are in the universe the want of ideas leaves open to our knowledge we have seen in the next place another cause of ignorance of no less moment is a want of discoverable connection between those ideas we have for wherever we want that we are utterly incapable of universal and certain knowledge and are in the former case left only to observation and experiment which how narrow and confined it is how far from general knowledge we need not be told I shall give some few instances of this cause of our ignorance and so leave it it is evident that the bulk figure and motion of several bodies about us produce in us several sensations as of colors sounds tastes smells pleasure and pain etc these mechanical affections of bodies having no affinity at all with those ideas they produce in us there being no conceivable connection between any impulse of any sort of body and any perception of a color or smell which we find in our minds we can have no distinct knowledge of such operations beyond our experience and can reason no otherwise about them than as effects produced by the appointment of an infinitely wise agent which perfectly surpass our comprehensions as the ideas of sensible secondary qualities which we have in our minds can by us be no way deduced from bodily causes nor any correspondence or connection be found between them and those primary qualities which experience shows us produce them in us so on the other side the operation of our minds upon our bodies is as inconceivable how any thought should produce a motion in body is as remote from the nature of our ideas as how any body should produce any thought in the mind that it is so if experience did not convince us the consideration of the things themselves would never be able in the least to discover to us these and the like though they have a constant and regular connection in the ordinary course of things yet that connection being not discoverable in the ideas themselves which appearing to have no necessary dependence one on another we can attribute their connection to nothing else but the arbitrary determination of that all wise agent who has made them to be and to operate as they do in a way wholly above our weak understandings to conceive 29 instances in some of our ideas there are certain relations habitudes and connections so visibly included in the nature of the ideas themselves that we cannot conceive them by any power whatsoever and in these only we are capable of certain and universal knowledge thus the idea of a right-line triangle necessarily carries with it an equality of its angles to two right ones nor can we conceive this relation this connection of these two ideas to be possibly mutable or to depend on any arbitrary power which of choice made it thus or could make it otherwise but the coherence and continuity of the parts of matter the production of sensation in us of colors and sounds etc by impulse and motion nay the original rules and communication of motion being such wherein we can discover no natural connection with any ideas we have we cannot but ascribe them to the arbitrary will and good pleasure of the wise architect I need not I think here mention the resurrection of the dead the future state of this globe of earth and such other things which are by everyone acknowledged to depend wholly on the determination of a free agent the things that as far as our observation reaches we constantly find to proceed regularly we may conclude do act by a law set them but yet by a law that we know not whereby though causes work steadily and effects constantly flow from them yet their connections and dependencies being not discoverable in our ideas we can have but an experimental knowledge of them from all which it is easy to perceive what a darkness we are involved in how little it is of being and the things that are that we are capable to know and therefore we shall do no injury to our knowledge when we modestly think with ourselves that we are so far from being able to comprehend the whole nature of the universe and all the things contained in it that we are not capable of a philosophical knowledge of the bodies that are about us and make a part of us concerning their secondary qualities powers and operations we can have no universal certainty several effects come every day within the notice of our senses of which we have so far sensitive knowledge but the causes manner and certainty of their production for the two foregoing reasons we must be content to be very ignorant of in these we can go no further than particular experience informs us of matter of fact and by analogy to guess what effects the like bodies are upon other trials like to produce but as to a perfect science of natural bodies not to mention spiritual beings we are I think so far from being capable of any such thing that I conclude it lost labor to seek after it thirty thirdly a third cause want of tracing our ideas thirdly where we have adequate ideas and where there is a certain and discoverable connection between them yet we are often ignorant for want of tracing those ideas which we have or may have and for want of finding out those intermediate ideas which may show us what habit of agreement or disagreement they have one with another and thus many are ignorant mathematical truths not out of any imperfection of their faculties or uncertainty in the things themselves but for want of application in acquiring examining and by do ways comparing those ideas that which has most contributed to hinder the do tracing of our ideas and finding out their relations and agreements or disagreements one with another has been I suppose the ill use of words it is impossible that men should ever truly seek or certainly discover the agreement or disagreement of ideas themselves whilst their thoughts flutter about or stick only in sounds of doubtful and uncertain significations mathematicians abstracting their thoughts from names and accustoming themselves to set before their minds the ideas themselves that they would consider and not sounds instead of them have avoided thereby a great part of that perplexity, puttering and confusion which has so much hindered men's progress in other parts of knowledge for whilst they stick in words of undetermined and uncertain signification they are unable to distinguish true from false certain from probable, consistent from inconsistent in their own opinions this having been the fate or misfortune of a great part of men of letters the increase brought into the stock of real knowledge has been very little in proportion to the schools disputes the world has been filled with whilst students being lost in the great wood of words knew not whereabouts they were how far their discoveries were advanced or what was wanting in their own or the general stock of knowledge had men in the discoveries of the material done as they have in those of the intellectual world involved all in the obscurity of uncertain and doubtful ways of talking volumes writ of navigation and voyages theories and stories of zones and tides multiplied and disputed nay ships built and fleets sent out would never have taught us the way beyond the line and the antipodes would still be as much unknown as when it was declared heresy to hold there were any but having spoken sufficiently of words and the ill or careless use that is commonly made of them I shall not say anything more of it here 31 extent of human knowledge in respect to its universality hitherto we have examined the extent of our knowledge in respect of the several sorts of beings that are there is another extent of it in respect of universality which will also deserve to be considered and in this regard our knowledge follows the nature of our ideas if the ideas are abstract whose agreement or disagreement we perceive our knowledge is universal for what is known of such general ideas will be true of every particular thing in whom that essence i.e. that abstract idea is to be found and what is once known of such ideas will be perpetually and for ever true so that as to all general knowledge we must search and find it only in our minds and it is only the examining of our own ideas that furnisheth us with that truth's belonging to essences of things is to abstract ideas are eternal and are to be found out by the contemplation only of those essences as the existence of things is to be known only from experience but having more to say of this in the chapters where I shall speak of general and real knowledge this may here suffice as to the universality of our knowledge in general