Aristotle's definition of the soul should be interpreted as: 'the soul is the entelechy of a natural body that serves as its instrument'. The theory of a fine-corporeal body makes it much easier to understand Aristotle's position between Plato and the Stoics . This correction puts paid to all theories about a development in Aristotle's thought.

Kepler's successful solution to the problem of vision early in the seventeenth century was a theoretical triumph as significant as many of the more celebrated developments of the scientific revolution. Yet the full import of Kepler's arguments can be grasped only when they are viewed against the background of ancient, medieval, and Renaissance visual theory. David C. Lindberg provides this background, and in doing so he fills the gap in historical scholarship and constructs a model for tracing the development of scientific ideas. David C. Lindberg is professor and chairman of the department of the history of science at the University of Wisconsin, Madison.