Ayn Rand, Atlas Shrugged

"You who prattle that morality is social and that man would need no morality on a desert island -- it is on a desert island that he would need it most. Let him try to claim, when there are no victims to pay for it, that a rock is a house, that sand is clothing, that food will drop into his mouth without cause or effort, that he will collect a harvest tomorrow by devouring his stock seed today -- and reality will wipe him out, as he deserves; reality will show him that life is a value to be bought and that thinking is the only coin noble enough to buy it.

"If I were to speak your kind of language, I would say that man's only commandment is: Thou shalt think. But a 'moral commandment' is a contradiction in terms. The moral is the chosen, not the forced; the understood, not the obeyed. Teh moral is the rational, and reason accepts no commandments.

"My morality, the morality of reason, is contained in a single axiom: existence exists -- and in a single choice: to live. The rest proceeds from these. To live, man must hold three things as the supreme and ruling values of his life: Reason -- Purpose -- Self-esteem. Reason, as his only tool of knowledge -- Purpose, as his choice of the happiness which that tool must proceed to achieve -- Self-esteem, as his inviolate certainty that his mind is competent to think and his person is wrothy of happiness, which means: is worthy of living. These three values imply and require all of man's virtues, and all his virtues pertain to the relation of existence and consciousness: rationality, independence, integrity, honor, justice, productiveness, pride.

[John Galt's address to the nation, Part III, Chapter VII, "This is John Galt Speaking"]