Envy is the basis of democracy.

Fear is the parent of cruelty, and therefore it is no wonder if cruelty and religion have gone hand-in-hand. It is because fear is at the basis of those two things. In this world we can now begin a little to understand things, and a little to master them by the help of science, which has forced its way step by step against the Christian religion, against the churches, and against the opposition of all the old precepts.

One's work is never so bad as it appears on bad days, nor so good as it appears on good days.

There are infinite possibilities of error, and more cranks take up fashionable untruths than unfashionable truths.

There is little of the true philosophic spirit in Aquinas. He does not, like the Platonic Socrates, set out to follow wherever the argument may lead.

Aristotle maintained that women have fewer teeth than men; although he was twice married, it never occurred to him to verify this statement by examining his wives' mouths.

I never held Negroes to be inherently inferior. The statement in Marriage and Morals refers to environmental conditioning. I have had it withdrawn from subsequent editions because it is clearly ambiguous.