What Did the Ancient Greeks Think About Dreams?

From prophecy and divine communication to medical diagnosis and understanding the human psyche, the ancient Greeks had many theories about why we dream.

The evolution of the theory of dreams in the ancient Greek world took many turns, with earlier Greeks believing all dreams were divinely inspired and that only the most important of people experienced them.

In his Iliad, widely acknowledged to have been written in the early seventh century BC, Homer describes a dream that Greek King Agamemnon has regarding the war with the defending power of Troy. It was a false dream sent to the ruler by Zeus.

The great poet wrote, “Go, deadly dream, along the Greek ships,” with Zeus commanding the dream so that “the dream listened and went” to Agamemnon. It is worth noting that the Greek soldiers did not doubt the dream, as it was gifted to a king. “If any other man told us this dream we would call it a lie and turn our backs on him,” Homer wrote.

Here, the ancient poet of the Iliad and the Odyssey embodies the non-scientific Greek interpretation of dreams in which he believed strongly.

Theories surrounding dreams in ancient Greece tended to form around polarities, such as whether a dream was true or false and possibly divine or natural.

For most ancient Greeks, the most significant function of dreams was to predict the future, and the initial steps taken to interpret a dream and render it “authentic” was to examine whether it was both sent by a god and true.

Ancient Greek Philosophers on the Nature of Dreams

Aristotle and a few others, however, took a more agnostic view of dreams. In his work On Dreams, written around the middle of the fourth century BC, Aristotle explained that, during sleep when the eyes are closed and unable to see, there is an absence of external sensory stimulation, and nothing is perceived by the sleeper.

He goes on to compare dreams to waking hallucinations, writing, “The faculty by which, in waking hours, we are subject to illusion when affected by disease, is identical with that which produces illusory effects in sleep.”

Aristotle ultimately came to the conclusion that dreams are due to residual movements of the sensory organs, and some dreams, the philosopher wrote, may even be caused by indigestion.

Like Aristotle, the ancient Greek philosopher Epicurus attributed dreams to a natural rather than divine origin. As written in the “Vatican Sayings,” a collection of quotes of Epicurus and other Epicureans preserved in a fourteenth century manuscript from the Vatican Library, the philosopher said “dreams have no divine nature nor any prophetic force but originate from the impact of images on the senses.”

There was a duality to the way Greek philosopher Plato understood dreams. He claimed dreams were one of the ways by which the gods shared their plans and intentions with humankind, as he wrote in Apology.

However, at the same time, Plato believed natural causes, including disturbances in the body’s internal motions, could give rise to dreams.

Dreams and Their Medical Implications

Hippocrates, a Greek physician from the classical period, also posited theories on the nature of dreaming. He placed emphasis on the role of dreams as a significant indicator of the dreamer’s physical condition and provided a theoretical basis for the use of dreams as insight into the condition of the body.

Moreover, he assigned dreams a very high status in his prodiagnostic theory. Hippocrates believed there were two types of dreams, namely those sent by the gods and those sent by the soul. Dream interpretation for the ancient Greeks was typically a way to determine the course of medical treatment.

Another peculiarity of ancient Greek culture was that many people believed the psyche, or soul, was revealed in sleep through the relaxed state of being people assume while asleep rather than the realms of dreams themselves. This is a state Aristotle referred to as the “borderland between living and not living.”