This is a quote from the book "The Virtue Of Selfishness" by Ayn Rand
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A government is the means of placing the retaliatory use of physical force under objective control — i.e., under objectively defined laws.
The fundamental difference betwe
en private action and governmental action — a difference thoroughly ignored and evaded today — lies in the fact that a government holds a monopoly on the legal use of physical force. It has
to hold such a monopoly, since it is the agent of restraining and combating the use of force; and for that very same reason, its actions have to be rigidly defined, delimited and circumscribed; ...