140 Quotes by Henri Poincare

All of mathematics is a tale about groups.

Mathematicians do not study objects, but relations among objects; they are indifferent to the replacement of objects by others as long the relations don't change. Matter is not important, only form interests them.

Doubt everything or believe everything: these are two equally convenient strategies. With either we dispense with the need for reflection.

Geometry is the art of correct reasoning from incorrectly drawn figures.

Need we add that mathematicians themselves are not infallible?

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.

In the old days when people invented a new function they had something useful in mind.

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.

Thought is only a flash between two long nights, but this flash is everything.