Analyse data just so far as to obtain simplicity and no further.

There are no solved problems; there are only problems that are more or less solved.

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

Mathematicians do not study objects, but relations among objects; they are indifferent to the replacement of objects by others as long the relations don't change. Matter is not important, only form interests them.

Logic sometimes makes monsters. For half a century we have seen a mass of bizarre functions which appear to be forced to resemble as little as possible honest functions which serve some purpose.

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.... The two propositions: "The earth turns round" and "it is more convenient to suppose the earth turns round" have the same meaning; there is nothing more in the one than in the other.

Mathematicians do not study objects, but the relations between objects.