A Harvard professor of economics has just released the fifth edition of Principles of Economics, a bestselling introductory economics textbook, and all across the world trees and and students have been falling in equal measure: the former have been severed by chainsaw-wielding maniacs in stump-filled ravines; the latter have been collapsing in their dormitories for want of sustenance, an entire month’s pittance diverted from the cafeteria to the campus bookstore, to fill the coffers of a grinning, bespectacled Bostonian.

On Greg Mankiw’s blog, of course, there is no mention of the money the professor will reap from the newest iteration of his textbook, which is selling on Amazon for a whopping $178.89. In a post dated to Saturday, October 11, Mankiw writes:

Why a new edition? The fundamentals of economics are much the same: Supply curves still slope up, and demand curves still slope down. But a lot has changed over the past three years, and the new edition covers recent developments in economic research, events, and policy. In particular, it includes over 40 new applications, including Case Studies and In the News boxes, to remind students that economics is about the world in which they live.

Indeed, much has changed in the past three years. (For example, look at how all those economic theories helped the Fed prevent our economy from tanking). But really, Mankiw, the readers of your introductory economics textbook are not the same Ivory Tower academes that receive a dozen canary-colored working papers from NBER each month. They’ll survive without 40 new applications, thank you very much.

When asked by email to detail the changes he made from the fourth edition to the fifth, Mankiw was not extremely helpful. He wrote: “contact brian joyner, who I mentioned on my blog post. he can give you some information.” The fact that Mankiw directed me to someone at the publisher of his textbook leads me to wonder whether he knows what he changed at all.

After the jump: an approximation of Mankiw’s rake on every textbook.

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