No other subject in economics has been studied longer or more intensively than the subject of money. The result is a vast amount of documented experience and a well-developed body of theoretical analysis. The extent to which the students of monetary problems agree in their basic conclusions is concealed by the tendency of laypersons to exaggerate their differences. But even among professional economists there remain important disagreements, centring mainly on empirical judgments about the stability and form of some of the relations between money and other economic phenomena.