Byzantine natural philosophy is heavily dependent on that of late antique Neoplatonic Aristotelianism, especially in the idiosyncratic form it took in the works of John Philoponus. In this tradition, nature is considered to be an inner principle of change (kinēsis) and stability (stasis), and natural philosophy is the branch of theoretical philosophy that studies such entities as are subject to change in accordance with nature, in contradistinction to mathematics and theology, the objects of which are exempt from change. The views of the late antique philosophers were mostly followed by the Byzantines as long as they were not perceived as contrary to the Christian faith. One view that was shared by most of the former but none of the latter is the view that the world is eternal. The Byzantines followed Philoponus in rejecting this view, rather than trying to harmonize it with creationism, as Proclus and others did. They also generally rejected views which seemed to entail it: thus the Aristotelian doctrine that the heavens are composed of an imperishable kind of body met with no support in Byzantium. Other features of Aristotelian-Ptolemaic cosmology were, however, readily accepted: the world according to most Byzantine writers is a system of nine nested spheres rotating at various speeds and in different directions (the ninth sphere being responsible for the diurnal motion from east to west) around the sublunary realm, where fire, air, and water form concentric layers with the small spherical earth at rest at the center. These elements are involved in a continuous cycle of transformation into one another, by virtue of each possessing one of the active qualities of hot and cold and one of the passive qualities of dry and moist. Some Byzantine writers, who found fault with Aristotle’s theory of place, also lent a willing ear to the Stoic cosmologist Cleomedes’ arguments in favor of the existence of extracosmic void. Philoponus’ influence is also obvious in the field of psychology, where most writers subscribe to an interpretation of Aristotle which leans strongly toward dualism: according to it, the lower soul faculties are inseparable from the body, but the rational soul, although dependent on the human body for some of its activities, is wholly separable from it in substance, and thus immortal.
Dordrecht ; London: Springer, 2011. 858-863 p.