A few words will suffice to justify the preparation of an introduction to English readers of Joseph de la Vega's Confusion de Confusiones. His book is the first that describes the practices of any stock exchange; it makes evident a high development of practices, with puts, calls, pools, and manipulations; and it appeared as early as the seventeenth century. Not inappropriately the stock exchange described is that of Amsterdam, a city which at the date of the volume's publication — 1688 — was still the leading financial center of the world. The book, to be sure, is hardly a systematic account of the institution; the author pursued moral, philosophical, and rhetorical objectives, and, while saying a lot that seems now to be of little value, manages somehow to leave unsaid a great deal that would be of interest for us. Nevertheless, it represents, even in its peculiar form, a really important source of information about the stock exchange, and indeed about the Dutch business world of that period.