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.

All that we can hope from these inspirations, which are the fruits of unconscious work, is to obtain points of departure for such calculations. As for the calculations themselves, they must be made in the second period of conscious work which follows the inspiration, and in which the results of the inspiration are verified and the consequences deduced.‎

It is through science that we prove, but through intuition that we discover.

It is by logic we prove. It is by intuition we discover.

What is a good definition? For the philosopher or the scientist, it is a definition which applies to all the objects to be defined, and applies only to them; it is that which satisfies the rules of logic. But in education it is not that; it is one that can be understood by the pupils.

A very small cause, which escapes us, determines a considerable effect which we cannot ignore, and we say that this effect is due to chance.

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