Solomon Lefschetz: «Don' t come to me with your pretty proofs. We don' t bother with that baby stuff around here»

Solomon Lefschetz (1884-1972) was a legend in 20th century mathematics. The father of algebraic topology, he is just as well known for his tough and eccentric character. 

At the beginning of a famous mathematician's lecture at Princeton, the mathematician said, "Let x be a point and y be a point." Lefschetz rose and asked, "Why didn't you just say 'Let x and y be points'?" The mathematician responded, "Because x and y may be the same point." Lefschetz stormed out of the room and never talked to that mathematician again.

Lefschetz placed infinite value on original ideas and sneered at the pursuit of rigorous proofs (not something necessarily recommended for the IMO!). When Lefschetz's students pointed out the slips in his proofs while proofreading for him, he would tell them not to pester him with their pretty proofs. His most famous book hardly contains one completely correct proof. Rumor has it that it was written during one of his sabbatical leaves, when his students did not have the opportunity to revise it.

Lefschetz lost both hands in an industrial accident in his twenties, and had wooden hands installed. (But I've seen his signature in the Fine Hall Professors' Lounge and it's quite exquisitely signed!) As Chair of Princeton's Math Department in the 1940s and 1950s, he would summon all first year graduate students, bang his wooden hands on the table, and say, "Whether you go to class or not, I don't give a damn." He wanted to plunge the students into independent research as quickly as possible. Out of this atmosphere came students like John Milnor, Lloyd Shapley, and John Nash.