The “how to” issue from Bloomberg Businessweek asks Nobel Prize-winning economist Paul Krugman to address a vital topic with which he is all too familiar: how to beat a dead horse.

Metaphors, if you can find good ones, are helpful. Sometimes you can mull over an issue for years before the right thing comes to you. “Confidence fairy” has been a good friend to me. That one just came out of the blue in 2010. “Zombie ideas” is not original with me, but it’s been very useful.

It also helps if you’re going to make the same point many times that it’s a very important point worth making.

It’s unfortunate that Professor Krugman does not add that making the same point many times makes more sense when that point is correct. Of course, that might put him out of business. But as long as people are willing to buy magical Keynesian thinking, the good professor is likely to remain employed.