Quoting again from PFA,
Figure 1 illustrates the implications of a theory of Keynesian economics without the consumption function. The aggregate demand curve does not slope upward with income; it is a horizontal straight line. The position of this line depends on the beliefs of market participants about the value of their financial assets. As the value of financial assets fluctuate, driven by self-fulfilling beliefs, so the aggregate demand curve moves up and down between the solid horizontal line and the dashed horizontal line. As people feel more or less wealthy, they buy more or fewer goods. Firms hire more or fewer workers and real GDP fluctuates between point YA* and YB*. (PFA, page 178.)
But although, I reject the simple Keynesian version of Aggregate Demand, I do not reject Keynesian economics. The key idea in the General Theory is that high involuntary unemployment may persist as an equilibrium of a market economy. How can that be? In Prosperity for All,
I provide a foundation—Keynesian search theory—to the Keynesian theory of aggregate supply. This new theory is rooted firmly in the microeconomic theory of behavior. According to Keynesian search theory, everything demanded will be supplied and any unemployment rate can be an equilibrium unemployment rate. (PFA pages 178-9.)
The implications of these ideas, taken as a package, are profound. If demand works through wealth, the right policy to maintain full employment is an intervention in the asset markets, not in the goods markets.