" 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