A sane mind should not be guilty of a logical fallacy yet there are very fine minds incapable of following mathematical demonstrations. Henri Poincare

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. Henri Poincare

Science is built up of 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. Henri Poincare

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. Henri Poincare

One would have to have completely forgotten the history of science so as to not remember that the desire to know nature has had the most constant and the happiest influence on the development of mathematics. Henri Poincare

What is it indeed that gives us the feeling of elegance in a solution in a demonstration? Henri Poincare

If one looks at the different problems of the integral calculus which arise naturally when one wishes to go deep into the different parts of physics it is impossible not to be struck by the analogies existing. Henri Poincare

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. Henri Poincare

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

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. Henri Poincare

The scientist does not study nature because it is useful; he studies it because he delights in it and he delights in it because it is beautiful. Henri Poincare

If that enabled us to predict the succeeding situation with the same approximation that is all we require and we should say that the phenomenon had been predicted that it is governed by the laws. Henri Poincare

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. Henri Poincare