One cannot demand of a scholar that he show himself a scholar everywhere in society, but the whole tenor of his behavior must none the less betray the thinker, he must always be instructive, his way of judging a thing must even in the smallest matters be such that people can see what it will amount to when, quietly and self-collected, he puts this power to scholarly use.

Everyone is a genius at least once a year. The real geniuses simply have their bright ideas closer together.

It is said that truth comes from the mouths of fools and children: I wish every good mind which feels an inclination for satire would reflect that the finest satirist always has something of both in him.

There is something in our minds like sunshine and the weather, which is not under our control. When I write, the best things come to me from I know not where.

The great trick of regarding small departures from the truth as the truth itself - on which is founded the entire integral calculus - is also the basis of our witty speculations, where the whole thing would often collapse if we considered the departures with philosophical rigour.

In every man there is something of all men.

One is rarely an impulsive innovator after the age of sixty, but one can still be a very fine orderly and inventive thinker. One rarely procreates children at that age, but one is all the more skilled at educating those who have already been procreated, and education is procreation of another kind.