This is a quote from the book "The Virtue Of Selfishness" by Ayn Rand
...cs is: no man may initiate the use of physical force against others. No man — or group or society or government — has the right to assume the role of a criminal and initiate the use of physi
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...
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