This work is designed to make Aristotle's three essays on sleep and dreams ( De Somno et Vigilia , De Insomniis and De Divinatione per Somnum ) accessible in translation to modern readers, and to provide a commentary with a contemporary perspective. It considers Aristotle's theory of dreams in historical context, especially in relation to Plato. It also discusses neo-Freudian interpretations of Aristotle and contemporary experimental psychology of dreaming. Aristotle's account of dreaming as a function of the imagination is examined from a philosophical perspective. Greek text, with facing-page English translation, introduction, notes and commentary.