For the first time since her return, she felt pain, a violent pain, but it made her feel alive, because it was worth feeling.

In a free society, one does not have to deal with those who are irrational. One is free to avoid them.

It was the greatest sensation of existence: not to trust but to know.

[Altruism] is a moral system which holds that man has no right to exist for his own sake, that service to others is the sole justification of his existence, and that self-sacrifice is his highest moral duty, value and virtue. This is the moral base of collectivism, of all dictatorships.

Civilization does not have to perish. The brutes are winning only by default.

Man's mind is his basic tool of survival. Life is given to him, survival is not. His body is given to him, its sustenance is not. His mind is given to him, its content is not. To remain alive, he must act, and before he can act he must know the nature and purpose of his action. He cannot obtain his food without a knowledge of food and of the way to obtain it. He cannot dig a ditch-or build a cyclotron-without a knowledge of his aim and of the means to achieve it. To remain alive, he must think

No concept man forms is valid unless he integrates it without contradiction into the sum of his knowledge.