Devotion to the truth is the hallmark of morality; there is no greater, nobler, more heroic form of devotion than the act of a man who assumes the responsibility of thinking.

There's nothing of any importance in life — except how well you do your work. Nothing. Only that. Whatever else you are, will come from that. It's the only measure of human value.

Indiscriminate tolerance and indiscriminate condemnation are not two opposites: they are two variants of the same evasion.

It's not a question of who will allow me to do it, it's a question of who will stop me.

God help us, ma'am! Do you see what we saw? We saw that we'd been given a law to live by, a moral law, they called it, which punished those who observed it - for observing it. The more you tried to live up to it, the more you suffered; the more you cheated it, the bigger reward you got. Your honesty was like a tool left at the mercy of the next man's dishonesty. The honest ones paid, the dishonest collected. The honest lost, the dishonest won. How long could men stay good under this sort of a law of goodness?

The ladder of success is best climbed by stepping on the rungs of opportunity.

The Middle Ages were an era of mysticism, ruled by blind faith and blind obedience to the dogma that faith is superior to reason. The Renaissance was specifically the rebirth of reason, the liberation of man's mind, the triumph of rationality over mysticism - a faltering, incomplete, but impassioned triumph that led to the birth of science, of individualism, of freedom.