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

How is error possible in mathematics?

But all of my efforts served only to make me better acquainted with the difficulty, which in itself was something.

Ideas rose in clouds; I felt them collide until pairs interlocked, so to speak, making a stable combination.

It may happen that small differences in the initial conditions produce very great ones in the final phenomena. A small error in the former will produce an enormous error in the later. Prediction becomes impossible, and we have the fortuitous phenomena.

[T]he different branches of Arithmetic - Ambition [G]eometry is not true, it is advantageous.

A cat is witty, he has nerve, he knows how to do precisely the right thing at the right moment.