Sad to hear that Raoul Bott passed away this week (via Peter Woit; see also Jaques and LuboÅ¡). Bott was one of the leading mathematicians of his time, but he was also an inspirational teacher and a warm human being. When we were grad students at Harvard, Ted Pyne and I would try to attend whatever class he was giving, even though they were invariably at 8:30 in the morning, a time that was probably chosen intentionally since they were always so popular. He had a joyful sense of humor, and was kind enough to help me out with some geometry questions relevant to a paper I was writing. A truly great man.
Update: Perhaps one story will give a flavor for Bott’s personality. In class one morning he was in the midst of explaining the Atiyah-Singer index theorem (one of the most important results in modern topology), when he paused and looked reflective. Then he said something like, “The first I heard of this kind of thing was at a party at Princeton. Just talking with one of those physicists, it may have been Wigner. He was explaining this idea, saying that something like this ought to be true. Unfortunately, I had had a few drinks, and I didn’t follow him so well. But Atiyah was standing next to me, and he was perfectly sober!” And he laughed at his own story with a sense of open delight.