The core of the doctrine consists in the proposition that the supply of money and the demand for it both affect its value. This proposition is probably a sufficiently good hypothesis to explain big changes in prices; but it is far from containing a complete theory of the value of money. It describes one cause of changes in prices; it is nevertheless inadequate for dealing with the problem exhaustively. By itself it does not comprise a theory of the value of money; it needs the basis of a general value theory. One after another, the doctrine of supply and demand, the cost-of-production theory, and the subjective theory of value have had to provide the foundations for the Quantity Theory.
Ludwig von Mises, The Theory of Money and Credit
capitalism, economics, freedom, money