This is a quote from the book "The Virtue Of Selfishness" by Ayn Rand
...e of error is committed by the man who declares that since man must be guided by his own independent judgment, any action he chooses to take is moral if he chooses it. One’s own independent ju
dgment is the means by which one must choose one’s actions, but it is not a moral criterion nor a moral validation: only reference to a demonstrable principle can validate one’s choices.
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Just as man cannot survive by any random means, but must discover and practice the principles which his survival requires, so man’s self-interest cannot be determined by blind desir...