Work is of two kinds: first, altering a position of matter at or near the earth's surface relatively to other such matter; second, telling other people to do so. The first kind is unpleasant and ill-paid; the second is pleasant and highly paid.

To be able to concentrate for a considerable time is essential to difficult achievement.

Patriots always talk of dying for their country and never of killing for their country.

The whole problem with the world is that fools and fanatics are always so certain of themselves, and wiser people so full of doubts.

To teach how to live with uncertainty, and yet without being paralyzed by hesitation, is perhaps the chief thing that philosophy in our age can still do for those who study it.