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

Mathematical discoveries, small or great are never born of spontaneous generation.

This harmony that human intelligence believes it discovers in nature - does it exist apart from that intelligence? No, without doubt, a reality completely independent of the spirit which conceives it, sees it or feels it, is an impossibility. A world so exterior as that, even if it existed, would be forever inaccessible to us. But what we call objective reality is, in the last analysis, that which is common to several thinking beings, and could be common to all; this common part, we will see, can be nothing but the harmony expressed by mathematical laws.

Why is it that showers and even storms seem to come by chance, so that many people think it quite natural to pray for rain or fine weather, though they would consider it ridiculous to ask for an eclipse by prayer.

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

There are no solved problems; there are only problems that are more or less solved.

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