Absolute space, that is to say, the mark to which it would be necessary to refer the earth to know whether it really moves, has no objective existence.

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.

Mathematics is the art of giving the same name to different things.

Invention consists in avoiding the constructing of useless contraptions and in constructing the useful combinations which are in infinite minority.