Recent thinking about American economic performance has been marked by alarm over the country's loss of its “competitive edge.” Most of this discussion is not rooted in an understanding of the historical origins of the economic leadership now thought to be in jeopardy. Modern economists tend to assume that the American advantage has been technological and dates from the remote recesses of history, about as far back as anyone really cares to go. In a volume on U.S. competitiveness, Harvey Brooks writes: “Both our firms and our government, long accustomed to being the technological leaders in almost every field, have until recently measured their performance against domestic rather than foreign competitors” (Bruce R. Scott and George C. Lodge, 1985, p. 331; emphasis added). For one country to maintain a technologically based advantage over others for long historical periods is anomalous, and surely calls for explanation. Indeed, it is difficult to see how policies can respond appropriately to “what we have lost” without knowledge of what it was that we had and how we got it.