Sleep and dreaming in Greek and Roman philosophy

Theories as to the function of sleep and dreaming have been with us since the beginning of recorded history. In Ancient Greece and Rome the predominant view of dreams was that they were divine in origin. This view was held not only in theory but also in practice with the establishment of various dream-oracles and dream interpretation manuals (Oneirocritica). However, it is also in the Greek and Roman writings, paralleling advances in philosophy and natural science, that we begin to see the first rationalistic accounts of dreaming. This paper reviews the evolution of such rational accounts focusing on the influence of Democritus, who provides us with the first rationalistic account of dreaming in history, and Aristotle, who provides us with the most explicit account of sleep and dreaming in the ancient world.