This is a quote from the book "The ​Virtue Of Selfishness" by Ayn Rand
... to trade a bushel of potatoes for a basket of eggs and, having received the eggs, refused to deliver the potatoes. Visualize what this sort of whim-directed action would mean in an industrial s ociety where men deliver a billion dollars’ worth of goods on credit, or contract to build multimillion-dollar structures, or sign ninety-nine-year leases.

A unilateral breach of
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...
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