Mises argued that the demand for money, or how much people want to hold, depends not just on the money supply but on individuals' subjective views of the economy. Buyers, sellers, & investors choose to hold or spend money based on personal expectations & needs. He therefore rejected the idea of money's neutrality, the claim that more money only raises prices proportionally. He argued that changes in the money supply affect interest rates, investment, & production, shaping real economic outcomes.