Mathematics is, I believe, the chief source of the belief in eternal and exact truth, as well as a sensible intelligible world.

No one gossips about other people's secret virtues.

Is there any knowledge in the world which is so certain that no reasonable man could doubt it?

Every housemaid expects at least once a week as much excitement as would have lasted a Jane Austen heroine throughout a whole novel.

From India to Spain, the brilliant civilization of Islam flourished. What was lost to christendom at this time was not lost to civilization, but quite the contrary.

Philosophy arises from an unusually obstinate attempt to arrive at real knowledge. What passes for knowledge in ordinary life suffers from three defects: it is cocksure, vague and self-contradictory. The first step towards philosophy consists in becoming aware of these defects, not in order to rest content with a lazy scepticism, but in order to substitute an amended kind of knowledge which shall be tentative, precise and self-consistent.

Some people would rather die than think.