The scientist does not study nature because it is useful; he studies it because he delights in it — Henri Poincare
The mathematical facts worthy of being studied are those which, by their analogy with other facts — Henri Poincare
It has adopted the geometry most advantageous to the species or, in other words, the most convenient. — Henri Poincare
If one looks at the different problems of the integral calculus which arise naturally — Henri Poincare
If we knew exactly the laws of nature and the situation of the universe at the initial moment — Henri Poincare
In the old days when people invented a new function they had something useful in mind. — Henri Poincare
Ideas rose in clouds; I felt them collide until pairs interlocked, so to speak, making a stable combination. — Henri Poincare