It has taken some time, but the history of science has finally come to be viewed as something more than the repository for "anecdote or chronology" that Thomas Kuhn described, with some frustration, in The Structure of Scientific Revolutions thirty-one years ago.¹ Indeed, the history of science is now rightly recognized as essential to the understanding of science. Good history enriches the conceptual repertoire available for understanding science — it reveals forgotten styles of theorizing and kinds of scientific theory, standards of evidence and theory choice, modes of scientific practice, and realms of methodological debate. In the philosophical research program developed by Larry Laudan, episodes drawn from the history of science serve as data against which debates about science — concerning, for example, scientific realism, standards of theory choice, or the aims of science — are tested, if not settled.² And perhaps most importantly, the history of science is now appreciated for its capacity to provide an understanding of science which emphasizes the historical contingency in its theories, aims, methods, and place in society. The undermining of the notion that there is an "essence' of science, accomplished largely by the examination of the history of science, is perhaps most directly responsible for the emergence of science studies in the United States; no such effect could be attributed to a mere repository for "anecdote or chronology."³