Paul Krugman's influence on American politics has become indispensible. At the same time, like most macroeconomists, he can underestimate the technological (read, entrepreneurial) revolution that's hit the real economy in recent years--you know, the business innovations whose details that other Times columnist sweats. It is clear from his work that government must (in Adam Smith's phrase) "facilitate commerce in general." But it is not always clear how. My review in The Nation of his prophetic book from 1999, The Return of Depression Economics, can be read here.