Henri Poincare

If nature were not beautiful, it would not be worth knowing, and if nature were not worth knowing, life would not be worth living.

As we can not give a general definition of energy, the principle of the conservation of energy signifies simply that there is something which remains constant.

If we knew exactly the laws of nature and the situation of the universe at the initial moment, we could predict exactly the situation of the same universe at a succeeding moment.

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

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 the name, above all a mathematician, experiences in his work the same impression as an artist; his pleasure is as great and of the same Nature.