The demand for certainty is one which is natural to man, but is nevertheless an intellectual vice. If you take your children for a picnic on a doubtful day, they will demand a dogmatic answer as to whether it will be fine or wet, and be disappointed in you when you cannot be sure.

A happy life must be to a great extent a quiet life, for it is only in an atmosphere of quiet that true joy dare live.

It is undesirable to believe a proposition when there is no ground whatever for supposing it true

The main thing needed to make men happy is intelligence.

Truth is a shining goddess, always veiled, always distant, never wholly approachable, but worthy of all the devotion of which the human spirit is capable.

Extreme hopes are born of extreme misery, and in such a world hopes could only be irrational.

Aristotle and Plato considered Greeks so innately superior to barbarians that slavery is justified so long as the master is Greek and the slave barbarian.