Well, Igor takes out a scratch sheet of paper and starts doing calculations, but somehow he can’t get it. Landau says, “Igor, you regard yourself as an educated adult, yet you’re incapable of performing such a simple task.”
When I read this, I took it as a personal criticism. I regarded myself, rather arrogantly, as a very educated person, but I had never heard of calculus in my life. I hadn’t the slightest idea what this sequence of symbols meant.
I decided, as a personal revenge on Landau, to study the subject up to the point where I could solve this exercise. Landau said, in the biography, “Don’t waste your time on mathematicians and lectures and so on — instead, find a book with the largest number of solved exercises and go through them all. That’s how you learn mathematics.” I went back to the library and found the mathematics book with the largest number of problems. The book was in Russian, and I didn’t know Russian, but a young linguist is not afraid to pick up another language.
So I devoted a whole winter to this, and after maybe a month and a half, I came to the point where I could actually do this integral. But I had inertia, so I kept going. I couldn’t stop. And toward the end of about three months, I realized two things. Number one, I was fairly good at this kind of silly manipulative exercise. Number two, maybe this is not the only way to study mathematics. So I looked around and found I could take a two years’ leave of absence from my job.