Originally published in 1991. Philoponus long commentary on Aristotle s definition of light sets up the major concerns, both in optics and theory of light, that is discussed here. Light was of special interest in Neoplatonism because of its being something incorporeal in the world of natural bodies and therefore had a special role in the philosophical analysis of the interpenetration of bodies and also as a paradigm for the soul-body problem. The material investigated in this book contains much about the physiology of vision as well as the propagation of light. Several chapters investigate...