 No matter how hard you try, you can never see me. You think you're seeing me right now, but actually you aren't. One of the most difficult things to do in philosophy, and one of the most important, is to understand the relationship between the mind and the world, between our representations of reality and reality itself. It can be really hard to understand the relationship between the mind and the world, because the mind often operates in the background, it's something we're not really aware of most of the time. So there's a little exercise that you can do to help you become aware of what the mind is doing. When you become aware and see what the mind is doing, then you'll get a taste for the relationship between the mind and the world. Let me give you an example. This evening I enjoyed a delicious lemon with my dinner. You can see it's freshly squeezed, half-cut lemon. And most people, if I were to ask them, what do you see right now? You're watching. What do you see? You'd probably say, well, you see a lemon, you see a lemon cut in half, and squeeze. But I can guarantee that's actually not what you're seeing. And it's probably not even what I'm seeing. So here's how I like to phrase it. Really try to see what you see. Don't see what you think you see. See what you actually see. And it is certainly the case that you right now are not seeing a lemon. You are seeing a bunch of yellow pixels on your computer screen that are moving around. Your mind, most likely unaware to you, is taking that sensory input and moving yellow blob and it is running it through a theory, a conceptual filter, behind the scenes that makes you think that you're seeing a lemon, when in reality you're just seeing yellow pixels. But I'm afraid we can take it one step farther. In fact, you're not even seeing a screen. You think you're seeing a screen. The screen itself is the same kind of constructed object. What you're actually seeing is a bunch of colors in your visual field. One part of your visual field, your mind is constructed to say this is a screen and one part of the screen is the little yellow blob that your mind has constructed to say that is a lemon. The same is true when we're talking about audio. Are you hearing my voice right now? Are you actually hearing my voice right now? Hear what you hear, not what you think you hear. What you actually hear is a bunch of sounds coming from your computer. So what this means is almost all of our lives are lived within a world of our own mental construction. Now don't get me wrong, I'm not saying there is no such thing as the external physical world. Everything exists in your mind. I'm not going that far, though some people do. I believe that there is such a thing as an external physical world. However, I recognize that the world as it appears to me is not necessarily the world as it is, and in a sense I have no access to the world as it is, the external world that is. What I actually see is the sensory input that is presented to my own consciousness. I can then consciously or subconsciously develop a theory about what I think the cause of those experiences are. So in the case of the lemon, my mind has developed a particular concept, a particular construction of what it means to be a lemon, and what lemons look like. That's a concept in my mind. That concept is fulfilled by the sensory data that I am receiving right now, and so I effortlessly think that I'm seeing a lemon. I am living in a world of my own concepts, which I assume to correlate to an external reality. Now this might seem like a bunch of esoteric, useless philosophizing, but in fact it has huge implications, especially when we're talking about metaphysics, with questions like what types of things exist in the world? Is there only physical stuff? Is there only mental stuff? Is there some mixture of physical and mental stuff? If you become aware of what your mind is doing, you can have a clearer answer to those questions, and my suspicion, in fact I'm very confident of this, is that the standard Western physicalist perspective that says in the most extreme form there is no such thing as mental stuff is completely backwards. People don't realize that what we think is obviously physical objects are actually theoretical constructions that our minds come up with to try to explain the sensory experiences that we're having. In one sense, the experience is more fundamental than what we think is causing the experience. The internal phenomenon is more fundamental in a sense than what we think is the external phenomenon. So when you go out and interact with the world, and you think the world is populated by a bunch of objects that are just by themselves categorized in different ways, take a minute and become aware of what you're aware of. See what you see, hear what you hear, and you'll find your mind is a very active participant in constructing the world around you.