Experience is a cruel but effective teacher

James Taranto argues something good will come from the Obama presidency:

This is not to deny that the Obama presidency has been ruinous. But sometimes the costliest mistakes are those from which we learn the most.

(I wonder if the same will be true of the recent revival of fiscal policy. Fiscal policy seemed to have died in the 1970s but was revived by George W. Bush. Paul Samuelson was quite delighted to see it come back in his last days, but he departed before he would see it fail. If fiscal policy goes dormant again, it will only be for a generation and then it will be revived. Its appeal to politicians as a justification for things they want to do for other reasons is just too great to put it in the grave.)