If one looks at the different problems of the integral calculus which arise naturally when one wishes to go deep into the different parts of physics, it is impossible not to be struck by the analogies existing.

Chance ... must be something more than the name we give to our ignorance.

A cat is witty, he has nerve, he knows how to do precisely the right thing at the right moment.

One geometry cannot be more true than another; it can only be more convenient.

When the physicists ask us for the solution of a problem, it is not drudgery that they impose on us, on the contrary, it is us who owe them thanks.

It may happen that small differences in the initial conditions produce very great ones in the final phenomena.

A first fact should surprise us, or rather would surprise us if we were not used to it. How does it happen there are people who do not understand mathematics? If mathematics invokes only the rules of logic, such as are accepted by all normal minds...how does it come about that so many persons are here refractory?