 This is a notion that was developed by psychologists many years ago. First of all, I have here some symbol cards. These are what are called the Zener cards. They've got bicycle backs on them, just for demonstration purposes. They're made rather gigantic. We have a circle, a plus mark, three wavy lines, a square, and a five point a star. That's one line, two lines, three, four, and five. They can't be very easily confused one for the other. That's why they were designed by a man named Zener in Switzerland many years ago. And I have here a piece of black paper, which is photographic black paper. It's quite opaque. And they got me a, I guess, a Manila envelope. No serial number or anything on it, but it has a clasp and glue. My goodness, the security in this place really is something. Now, I want to step down into the audience for a moment here and just approach any, this lady who's sitting in there, would you mind to take this from me? Yes, thank you. I'm going to step back up to the stage and I would like you to follow my instructions if you would be so kind. First of all, take the five cards that you have in your hand, face down, and shuffle them up. Mix them very thoroughly so you don't know which card is which. You can't do a shuffle with them like that because they're very large and there are only five of them. Mix them up very thoroughly again so that you or no person here will know which card is which. Have you done that now? Is that done? Oh, there you are, okay. Now, I'm going to ask you to take three of them, keeping everything face down and put them on the floor underneath your chair, face down, and keep the other two face down in your hands. Have you done that now? The two that you have in your hand, this is the tricky part, look up at me here for a moment. You've got two of them like that, look away and quickly turn the two of them face to face. Done? Okay, you don't know what those cards are, am I correct? Okay, take the two cards and put them inside the piece of black paper, it just opens up like a little book there, place them inside, and then take that whole package and put it inside the envelope and you can either use the glue or the clasp or both if you wish. I'm taking all kinds of chances today. When you've got that done, I will come down to the audience and face you once more. Is it all sealed up now? Okay, now I can't see the other cards if I come down there, I can't even see the backs of them because you know, tricky me, I might have them marked or something like that. So I'll look away from you and you can just pass the envelope down to me and then we have it. Thank you very much. Now this I can tell, okay, this is the plain side of it, we'll call this the front, we'll call that the back, because this is the back and this is the front that's logical enough. Now where's my big black magic marker? There it is. Now, what are the chances, listen carefully now, I'm rooting it very carefully, what are the chances that I will be able to guess one card inside that envelope? Just one card, now there are two cards in there, but what are the chances that I'll be able to guess one card? It's all I have to know. This is the easy part, it gets more difficult. Very good, one in five. These are scientists, there's no question of it. Okay, one chance in five that I will be able to guess one card that's inside the envelope. Second part is even more difficult. What are the chances that I can guess both cards? Suppose I told you, all right, one in, one in 20? How do you get that? One over five times one over four? That would be one in 20, but I haven't said the important part. So suppose I were able to tell you, for example, that one of the cards is the plus mark, the one with the two lines, and the other one is the simple circle. Okay, suppose I were able to tell you that. Now, the chances of that will be one in 10, not one in one over five times one over four, but if I'm able to tell you, for example, that on the back side of the envelope, it would be the plus mark, and on the front side, it'll be the zero, the circle. If I were able to tell you in order, in which order they are, I've got half as much chance, so it is one in 20. Okay, now what did I just say? I just said to you that I believe that an imaginary marker will do it. I will mark right on the envelope so that I cannot change my mind later on. If I change my mind later on, that's not fair. I will mark a circle on here like that, very indelibly on this side. What did I say the other one was? Have you forgotten already? Plus mark, very good, okay. I will mark the plus mark on here, like that, okay. Now, the pen dries out very quickly in this atmosphere. I have marked the envelope indelibly in such a way that I cannot change my mind, excuse me. Let's see whether or not I am correct. On this side, I said the circle. On the other side, I said the plus mark. Let's see if I'm correct. My golly, the circle and the plus mark. Now, ladies and gentlemen, I'm gonna ask you the question again. What are the chances that I would be able to tell you which ones are where in the envelope? It's not one in 10 or one in 21 and five, one in 25. It's one in one because this is a trick. That's the trick part of the question, folks. This is a trick. When David Carverfield goes to cut a girl in half with a buzz saw, what are the chances that she's gonna survive? One in a billion or something? No, one in one because it's a trick. Let's get real here, folks. Scientists tend to look at the statistics, sort of think of the chances. When John Edward, the guy who talks to the dead on the sci-fi channel, now going into syndication on a network incidentally, doesn't that scare you? He speaks with the dead, right? And a scientist at the University of Arizona, Gary Schwartz, worked out the probabilities of it. If he says in a crowd like this, I'm getting a Michael. Wait a minute, I'm getting a Michael? Does that mean you're having a connection to some guy? What does it mean I'm getting a Michael? And he waits for someone to react. What are the chances of that being correct? Well, he says, how many men out of how many men are named Michael? And he works out the proportion of Michael's that there are probably gonna be represented. How many people does each person in the audience probably know, living or dead, that might be Michael? Oh my goodness, the chances are only one in about 900 that he would be right on that. Get out of here. He works out the statistics for something that is a trick. Right back to David Carverfield. What are the chances the girl's gonna survive the buzz saw? One in one. It's that simple.