Ayn Rand, Atlas Shrugged

"That which you call your soul or spirit is your consciousness, and that which you call 'free will' is your mind's freedom to think or not, the only will you have, your only freedom, the choice that controls all the choices you make and determines your life and your character.

"Thinking is man's only basic virtue, from which all the others proceed. And his basic vice, the source of all his evils, is that nameless act which all of you practice, but struggle never to admit: the act of blanking out, the willful suspension of one's consciousness, the refusal to think -- not blindness, but the refusal to see; not ignorance, but the refusal to know. It is the act of unfocusing your mind and inducing an inner fog to escape the responsibility of judgment -- on the unstated premise that a thing will not exist if only you refuse to identify it, that A will not be A so long as you do not pronounce the verdict 'It is.' Non-thinking is an act of annihilation, a wish to negate existence, an attempt to wipe out reality. But existence exists; reality is not to be wiped out, it will merely wipe out the wiper. By refusing to say 'It is,' you are refusing to say 'I am.' By suspending your judgment, you are negating your person. When a man declares: 'Who am I to know?' -- he is declaring: 'Who am I to live?'

"This, in every hour and every issue, is your basic moral choice: thinking or non-thinking, existence or non-existence, A or non-A, entity or zero.

"To the extent to which a man is rational, life is the premise directing his actions. To the extent to which he is irrational, the premise directing his actions is death."

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