Friedman identified his “natural rate” as Walrasian equilibrium. Keynes’s “full employment” is also classical equilibrium: labor markets are clearing at existing real wages. Why is equilibrium unemployment not zero? Keynes and Friedman cite, but do not explain, “frictional” unemployment. They differ on what explains cycles. Friedman and Lucas answer: misperceptions of inflation. Markets clear at wrong prices and quantities. Today New Classicals stress variations in the natural rate itself. In Keynesian cycles markets don’t clear. Excess supplies or demands trigger Phillips-curve movements of wages and prices. Unemployment and vacancies coexist in varying proportions because inter-sectoral shocks always occur. Adjustment dynamics, not represen...