Murray Gell-Mann: Just a slip of the tongue. That’s how I figured out the explanation of strangeness. I had come up with an incorrect explanation, which had some features in common with the correct one, but was wrong. And I knew why it was wrong. And another fellow had gotten the same idea, and figured out that it was wrong, and had written a letter about it, which was published. I hadn’t published anything. But he had published the idea, plus the reason why it was wrong, but in a very confused manner, so that it was extremely difficult to follow. I hadn’t even read it, but I knew what it was, because I had the idea, and I knew why it was wrong. And when I visited the Princeton Institute for Advanced Study, where I had been working a short time before, the theoretical physicist there asked me to explain how this worked, how the idea went and why it was wrong. And I said, “Yes, I can do that.” So I went to the blackboard and I started explaining the idea, and explaining why it was wrong. Partway through I made a slip of the tongue, and I realized that the slip of the tongue made it okay, the arguments against no longer were valid, and this was probably the right answer. That was how I found the strangeness theory.