A Consistent Macroeconomic Approach Would Have to Shun Any Reference to Prices and to Money

The macroeconomist deceives himself if in his reasoning he employs money prices determined on the market by individual buyers and sellers. A consistent macroeconomic approach would have to shun any reference to prices and to money. The market economy is a social system in which individuals are acting. The valuations of individuals as manifested in the market prices determine the course of all production activities. If one wants to oppose to the reality of the market economy the image of a holistic system, one must abstain from any use of prices.

—Ludwig von Mises, The Ultimate Foundation of Economic Science: An Essay on Method (Princeton, NJ: D. Van Nostrand Company, 1962), 84.