“Little by little his conversation, always instructive and animated, gave a special direction to my tastes, which would have led me by preference towards letters. I resolved to complete my scientific studies and followed the courses in advanced mathematics given by M. [Jean Guillaume] Gamier. It was at the same time agreed by us that, in order to relieve him in his work, I should give some of the other courses with which he was charged. I thus found myself his pupil and his colleague.”