It is with logic that one proves; it is with intuition that one invents.

We also know how cruel the truth often is, and we wonder whether delusion is not more consoling.

The mathematical facts worthy of being studied are those which, by their analogy with other facts, are capable of leading us to the knowledge of a physical law. They reveal the kinship between other facts, long known, but wrongly believed to be strangers to one another.

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.

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.

Sociology is the science with the greatest number of methods and the least results.

Just as houses are made of stones, so is science made of facts.