Suppose that for some reason you decided to start hitting yourself in the head, repeatedly, with a baseball bat. You’d feel pretty bad. Correspondingly, you’d probably feel a lot better if and when you finally stopped. What would that improvement in your condition tell you?

It certainly wouldn’t imply that hitting yourself in the head was a good idea. It would, however, be an indication that the pain you were experiencing wasn’t a reflection of anything fundamentally wrong with your health. Your head wasn’t hurting because you were sick; it was hurting because you kept hitting it with that baseball bat.

And now you understand the basics of what has been happening to several major economies, including the United States, over the past few years. In fact, you understand these basics better than many politicians and commentators.
—Paul Krugman, The Obama Recovery