ABSTRACT
This chapter looks at a central notion used in medieval natural philosophy and magic: the properties of creatures and substances, called proprietas, vis, virtus (or virtus specifica), qualitas or even natura. The importance of this concept comes from its use both in traditional Western thought, in order to define the nature of a thing or physical action, and in Arabic medicine, as an essential concept to explain a transformation or an effect. The first half of the thirteenth century was the time when these disciplines came together most intensely, because it was the period when we see the assimilation of Aristotle’s natural philosophy and its commentators, and of the works of Arab physicians and philosophers which had been translated into Latin during the last hundred and fifty years. We also see in thirteenth-century scholasticism a growing curiosity about nature and about the science of the soul’s faculties (“psychology”, coming from the De anima of Aristotle), and a growing importance given to causation, all of which enhanced considerably theories of knowledge and the study of perceptions and sensations. In this period, the comprehensive notion of natural property served equally to describe and define nature for educational purposes, and to explain natural or magical properties for therapeutic or prophylactic purposes. Therefore, it helps us to address the intellectual context of the birth of natural magic in medieval Europe as a peripheral branch of natural philosophy.
