President Obama has taken his fair share of flak for not following through on campaign promises--from renegotiating NAFTA to reforming immigration to ending Don’t Ask Don’t Tell. But there’s a slightly more obscure pledge--one he made at a March 2008 town hall meeting in Greensburg, Pennsylvania--that he may want to revisit.

“I will seriously consider eliminating the penny,” then-candidate Obama said, in response to a voter who questioned the wisdom of producing coins so worthless that vending machines (and some stores) no longer accept them. At the time, a growing media mob of economists and their public allies were pointing their pitchforks at the penny. And their case was ironclad--or, rather, zinc-clad: The soaring price of the penny’s primary ingredient had pushed the mine-to-mint production cost of each cent from .97 cents in FY 2005 to 1.67 cents in FY 2007 (at an annual loss of $54 million--or “negative seignorage,” in coin-speak).

But the penny’s prospects soon brightened, as the economic meltdown drove zinc prices down and led the U.S. Mint to produce fewer coins of all stripes (one-third as many pennies this year as in 2007). The coin was still a net loser for the American taxpayer, but a few million dollars in waste couldn’t spark the populist outrage that $700 billion in bank bailouts could. And so, the kill-the-penny zeitgeist died down.

It’s time to revive it.

Until last September, when the banking industry came crashing down and depression loomed for the first time in my lifetime, I had never thought to read The General Theory of Employment, Interest, and Money, despite my interest in economics. I knew that John Maynard Keynes was widely considered the greatest economist of the twentieth century, and I knew of his book's extraordinary reputation. But it was a work of macroeconomics--the study of economy-wide phenomena such as inflation, the business cycle, and economic growth. Law, and hence the economics of law--my academic field--did not figure largely in the regulation of those phenomena. And I had heard that it was a very difficult book, which I assumed meant it was heavily mathematical; and that Keynes was an old-fashioned liberal, who believed in controlling business ups and downs through heavy-handed fiscal policy (taxing, borrowing, spending); and that the book had been refuted by Milton Friedman, though he admired Keynes's earlier work on monetarism. I would not have been surprised by, or inclined to challenge, the claim made in 1992 by Gregory Mankiw, a prominent macroeconomist at Harvard, that "after fifty years of additional progress in economic science, The General Theory is an outdated book. . . . We are in a much better position than Keynes was to figure out how the economy works."

The Forgotten Man: A New History of the Great Depression By Amity Shlaes (HarperCollins, 464 pp., $26.95)

Herbert Hoover By William E. Leuchtenburg (Times Books, 208 pp., $22)

Nothing to Fear: FDR's Inner Circle and the Hundred Days that Created Modern America By Adam Cohen (Penguin Press, 372 pp., $29.95)