There are only two lasting bequests we can hope to give our children. One of these is roots, the other, wings.

Everything factual is, in a sense, theory. The blue of the sky exhibits the basic laws of chromatics. There is no sense in looking for something behind phenomena: they are theory.

Only the soul that loves is happy

People are always talking about originality, but what do they mean? As soon as we are born, the world begins to work upon us, and this goes on to the end.

The best genius is that which absorbs and assimilates everything without doing the least violence to its fundamental destiny.

How many years must a man do nothing, before he can at all know what is to be done and how to do it!

We are never deceived; we deceive ourselves.