This is a quote from the book "The Virtue Of Selfishness" by Ayn Rand
...cal compulsion against any man. Men have the right to use physical force only in retaliation and only against those who initiate its use. The ethical principle involved is simple and clear-cut:
it is the difference between murder and self-defense. A holdup man seeks to gain a value, wealth, by killing his victim; the victim does not grow richer by killing a holdup man. The principle is
: no man may obtain any values from others by resorting to physical force.
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The only proper, moral purpose of a government is to protect man’s rights, which means: to protect him ...