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.

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...

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

How is an error possible in mathematics?

Geometry is not true, it is advantageous.

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...

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

It has adopted the geometry most advantageous to the species or, in other words, the most convenient.

To doubt everything, or, to believe everything, are two equally convenient solutions; both dispense with the necessity of reflection.

Hypotheses are what we lack the least.