Aristotle on What is Seen in the Dark

Abstract

In De Anima II 7, Aristotle identifies two visible objects: color and an unnamed thing seen in the dark. Many scholars have identified the latter with phosphorescence. I argue that this identification is mistaken on both historical and philosophical grounds: Aristotle had no concept of phosphorescence, and most of his examples have nothing to do with it. Drawing on De Sensu 2, 437a31–b10, where Aristotle explains that smooth things shine in the dark because they are highly reflective, I propose that these things are seen at night not because they produce their own light but because their smooth surfaces reflect dim light. The paper also discusses Themistius and Philoponus, who held that these objects produce a weak light of their own. The proposed account offers a unified theory of vision: both color and the nameless thing seen in the dark require some light to be perceived.