The Law of Demand is one of the fundamental laws of economics. The Law of Demand is also an elementary fact of reality to which all businesses must adjust, the fact refuting the notion that businesses can raise their prices at their whim. These lectures will explain the flaw in economics' traditional explanation for the Law of Demand and suggest a new method of validating the Law, rooting it in the value structure of a rational animal. The importance of the Law will be demonstrated by showing how the Law underlies many everyday economic phenomena.