Marina Ratner, an influential mathematician and Russian-Jewish émigré who defied the notion that the best and the brightest in her field do their finest work when they are young. She embarked on her major work after age 40.

Étienne Ghys, a mathematician at École Normale Supérieure de Lyon in France, recalled spending six months trying to understand the results of Dr. Ratner’s dynamics research to present them at a seminar. When he discussed the papers with her, he told her that he had the feeling that she had written the papers not for other mathematicians to understand but mainly to convince herself that the theorems were correct.

Dr. Ghys said Dr. Ratner replied: “Yes! Exactly! You understood why and how I write mathematics.”

Ultimately, Dr. Ratner worked hard to satisfy her inner needs. She wasn’t looking to get hired by a university and she wasn’t trying to provoke her colleagues.

I wonder if David Callet ever met my therapist? I think they’d get on just great.