The teacher at MIT, my teacher, who is still alive, Victor Weisskopf, was a wonderful, inspiring person — is still a wonderful inspiring person. He is really a splendid person, and working with him was marvelous. First of all it was fun, but second I really learned something. Not a fact or a theory particularly, but I learned a principle, which was that fancy mathematics doesn’t have any value in science for it’s own sake. It may be useful to introduce some new mathematics, some fancy mathematics, because it helps you to get the answer. Helps you to formulate a new theory. Helps you to solve an old one. But just doing it for it’s own sake, just snowing people with mathematics is not a good idea. You should use methods that are as simple as possible, given the richness of the material, the depth of the theory that you are applying it to. That was very important, because graduate students are frequently impressed with formalism. And Victy just refused to be impressed with formalism. He said, “That doesn’t matter. It’s just formalism.” What matters is making a new discovery, a new theoretical discovery, not with just improving the formalism. Improving the formalism may prove useful for making a new discovery, and in that case it’s fine, but otherwise it is not to be valued. Don’t be impressed by formal developments, be impressed by real developments. That was very important for me.