That "out and then back" theoretical possibility requires a god-like policy maker to time market and engage in counter-cyclical interventions. Given Keynes' own investment track record of losing almost all of his own personal fortune in the stock market crash, it's safe to assume that not even Keynes himself would be able to spot when to make the money pump flow "back." As for when to pump forward and increase money supply, that's easy . . . anyone ever heard of a counterfeit machine can understand the joy in pulling the lever on that one. Keynes' "out and then back" theory is little more than the "Divine Rights" theory about the absolute monarchy: he is supposed to exercise his absolute power wisely and in the interest of his people. We all know that doesn't work. Check and balance works out better for societal stability, likewise, central banking is nowhere nearly as stable or enduring as multiple banks competing for the voluntary acceptance of their banknotes by economic producers.
Market Data 
Markets 
