The only truths which are universal are those gross enough to be thought so.

History is the most dangerous product evolved from the chemistry of the intellect. ...History will justify anything. It teaches precisely nothing, for it contains everything and furnishes examples of everything.

Every social system is more or less against nature, and at every moment nature is at work to reclaim her rights.

Beware of what you do best; its bound to be a trap.

No work of art is ever completed, it is only abandoned.

The purpose of psychology is to give us a completely different idea of the things we know best.

In the physical world, one cannot increase the size or quantity of anything without changing its quality. Similar figures exist only in pure geometry.