[Keynes argued that] money...was an inherently political tool. It was the state that determined what substance—gold, paper, whatever—actually counted as money—what “thing” people and the government would accept as valid payment. The state thus created money and had always regulated its value.... The very idea of capitalism required active state economic management—the regulation of money and debt.

Zachary D.Carter in The Price of Peace

That our opinion gives the value to things is very manifest in the great number of those which we do, not so much prizing them, as ourselves, and never considering either their virtues or their use, but only how dear they cost us, as though that were a part of their substance; and we only repute for value in them.... as it weighs, it serves for so much as it weighs.... the price gives value to the diamond.

Michel de Montaigne