Aggregate Demand ll Science is a parasite: the greater the patient population the better the ad ance in physiology and pathology; and out of pathology arises therapy The year 1932 was the trough of the great depression, and from its rotten soil was belatedly begot a new subject that today we call macroeconomics In Chapter 10 we assembled the pieces of the IS-LM model. We saw that the IS curve represents the equilibrium in the market for goods and services, that the LM curve represents the equilibrium in the market for real money balances, and that the IS and LM curves together