This is a quote from the book "The Virtue Of Selfishness" by Ayn Rand
... contract involves an indirect use of physical force: it consists, in essence, of one man receiving the material values, goods or services of another, then refusing to pay for them and thus keep
ing them by force (by mere physical possession), not by right — i.e., keeping them without the consent of their owner. Fraud involves a similarly indirect use of force: it consists of obtainin
g material values without their owner’s consent, under false pretenses or false promises. Extortion is another variant of an indirect use of force: it consists of obtaining material values, no...
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