At Harvard I took both math and physics courses all the way through, but I knew which was my subject. In mathematics, any principle you learned was simply true: you could apply it anywhere you liked and you’d never reach a falsehood. In physics, that wasn’t enough. You had to have some kind of deeper understanding to see that *this* principle was appropriate *here* and *that* one could be applied *there*. It made me uneasy.

Forty years on, what kind of mathematician have I become? One whose pride is that he doesn’t apply principles blindly but guided by deeper understanding! Indeed, not long ago I published an essay on “Inverse Yogiisms” all about mathematicians’ habit of following rigorous logic to misleading, though mathematically valid, conclusions.

Which brings me to two thoughts. One is that maybe I could have been a pretty good physicist after all. The other is that as a physicist, maybe I would have been a little less distinctive.

[3 February 2019]