It is the harmony of the diverse parts, their symmetry, their happy balance; in a word it is all that introduces order, all that gives unity, that permits us to see clearly and to comprehend at once both the ensemble and the details.

A scientist worthy of his name, about all a mathematician, experiences in his work the same impression as an artist; his pleasure is as great and of the same nature.

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?

It is by logic that we prove, but by intuition that we discover. To know how to criticize is good, to know how to create is better.

One does not ask whether a scientific theory is true, but only whether it is convenient.

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

Science is built up with facts, as a house is with stones. But a collection of facts is no more a science than a heap of stones is a house.