The message is this: Paul Krugman wrote an economics textbook. You should buy it.

In the April issue of The Atlantic, Michael Kinsley suggested that we should be more worried about inflation. Krugman, from his blog, accused Kinsley of ignoring "textbook economics." At this, Kinsley dutifully paged through Greg Mankiw's introductory economics textbook, but failed to find the information Krugman was referring to, and said so. Clearly, he missed the point, as Krugman explained patiently in his response:

Kinsley says that he looked at Greg Mankiw's text and found no such distinction; strange to say, however, it wasn't Mankiw's text I had in mind. Instead, I was thinking of another intro text that sells quite a few copies, although not (yet?) as many as Mankiw.
As the hyperlinked text showed (it's in the original), Krugman was thinking instead of his own economics textbook. Kinsley--a quick learner--promptly inserted links to both Krugman's and Mankiw's books on Amazon in his next response.

Now it has happened again. Wednesday, The Economist ran a story about how the financial crisis is beginning to be worked into economics textbooks. The article points to revisions in textbooks by Stanford's Charles Jones, Princeton's Alan Blinder, and--again--Harvard's Greg Mankiw.

"So What Are We, Chopped Liver?" asks Krugman the headline of his post. "Strange to say, the article doesn't mention the 3rd best-selling textbook--or maybe 2nd, we’re having a really good year--which already covers that ground, thanks to a frantic revision (in second-pass pages) in fall 2008."

What does a Nobel prize-winning, New York Times columnist of a Princeton professor have to do to sell a book around here?