Geometry is not true, it is advantageous.

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.

One does not ask whether a scientific theory is true, but only whether it is convenient.

Doubting everything and believing everything are two equally convenient solutions that guard us from having to think

The mind uses its faculty for creativity only when experience forces it to do so.

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.

If we wish to foresee the future of mathematics, our proper course is to study the history and present condition of the science.