The harm that theology has done is not to create cruel impulses, but to give them the sanction of what professes to be lofty ethic, and to confer an apparently sacred character upon practices which have come down from more ignorant and barbarous times.

There are three ways of securing a society that shall be stable as regards population. The first is that of birth control, the second that of infanticide or really destructive wars, and the third that of general misery except for a powerful minority.

Envy ... is one form of a vice, partly moral, partly intellectual, which consists in seeing things never in themselves but only in their relations.

Always remember that true happiness is not in getting what you want, but wanting what you already have. He who dies with the most toys is still dead. What is wanted is not the will to believe, but the will to find out, which is the exact opposite.

In spreading his ideas, Plato was willing to employ emotional appeals, state propaganda, and the use of force.

You may reasonably expect a man to walk a tightrope safely for ten minutes; it would be unreasonable to do so without accident for two hundred years.

Men fear thought as they fear nothing else on earth - more than ruin, more even than death. Thought is subversive and revolutionary, destructive and terrible, thought is merciless to privilege, established institutions, and comfortable habits; thought is anarchic and lawless, indifferent to authority, careless of the well-tried wisdom of the ages. Thought looks into the pit of hell and is not afraid ... Thought is great and swift and free, the light of the world, and the chief glory of man.