He who does not know foreign languages does not know anything about his own.

I have heard myself accused of being an opponent, an enemy of mathematics, which no one can value more highly than I, for it accomplishes the very thing whose achievement has been denied me.

As in Rome there is, apart from the Romans, a population of statues, so apart from this real world there is a world of illusion, almost more potent, in which most men live.

If in the infinite you want to stride, Just walk in the finite to every side.

Do people conform to the instructions of us old ones? Each thinks he must know best about himself, and thus many are lost entirely.

Basic characteristics of an individual organism: to divide, to unite, to merge into the universal, to abide in the particular, to transform itself, to define itself, and as living things tend to appear under a thousand conditions, to arise and vanish, to solidify and melt, to freeze and flow, to expand and contract. Since these effects occur together, any or all may occur at the same moment.

When you take a man as he is, you make him worse. When you take a man as he can be, you make him better.