Posner becomes a Keynesian

Richard Posner writes in the New Republic about how he became a Keynesian. Worth reading, despite his confusion over the difference between savings and investment. Perhaps the problem is Posner's inability to use the word equilibrium condition. For Keynes point was that savings equals investment in equilibrium and that changes in income bring this about. Without this the article is confusing about passive and active investment and so on.

I need to write more about the contribution of Keynes to understanding this crisis.