Matter of Sleep. Byzantine Commentators of the 12th – 15th centuries on the Material Cause of Sleep in Aristotle’s Treatise On Sleep and Waking (De Somno et Vigilia)

Abstract

The paper gives a general description of the surviving Byzantine commentaries on Aristotle’s small psychological treatises traditionally known as Parva naturalia and describes the most notable manuscripts and editions of commentaries compiled by Michael of Ephesus, George Pachymeres, Theodore Metochites, Sophonias and Gennady Scholarios. The paper clarifies relationships of these texts to each other, discusses possible reasons of the renewal of interest in biological and physiological aspects of Aristotle’s philosophy among Byzantine scholars of the 12th – 15th centuries, and explains why the late antique commentary tradition paid little attention to particular issues of Aristotle’s philosophy of nature. Distinctive features of Byzantine exegesis are established by examining how Byzantine commentators dealt with some controversial questions of Aristotle’s treatise On sleep and waking, in particular the question of why Aristotle, after promising to consider the formal, final, effective and material causes of sleep, explores only three of these causes and leaves the material one without attention. We demonstrate that Byzantine commentators were convinced of the existence of the material cause of sleep and identified the latter with the hot evaporation that necessarily arises from food in the process of digestion. However, the analysis of this interpretation shows that it was based on a misunderstanding of the basic concepts of Aristotelian philosophy, since Byzantine exegesis was aimed more at preserving Aristotle's texts than at better understanding the general order of his philosophy.