Long before metaphor had a name, the ancient Greeks were already practising the intellectual manoeuvre at its heart: looking at one thing and understanding that it might mean another.
A new study by Princeton classicist Mirjam Kotwick argues that the interpretation of dreams became an unlikely laboratory for some of the earliest Greek thinking about language, symbolism and hidden meaning. In The Ancient Interpretation of Dreams: Early Greek Hermeneutics and Its Sources, published this year by Princeton University Press, Kotwick traces a tradition stretching from Homer through Aeschylus, Herodotus, the Hippocratic writers, Plato and Aristotle. Her larger proposition is striking. The way the Greeks learned to decipher dreams may have helped shape the way we still interpret metaphor, allegory and literature today.
The story begins, appropriately, with Penelope.
In Book 19 of Homer’s Odyssey, Odysseus’s wife recounts a disturbing dream. Twenty geese are feeding at her palace when an eagle descends and kills them. Penelope weeps, until the eagle returns and speaks in a human voice. The geese, it explains, are her suitors. The eagle is Odysseus, returned home to destroy them.
It is among the earliest surviving examples of Greek dream interpretation, although Kotwick is careful not to describe it as the beginning of the practice itself. Dream interpretation was already well established in older cultures, including Mesopotamia and Egypt. Homer inherited a world in which dreams could carry messages. What interests Kotwick is how the Greeks went about extracting those messages.
Her term for the method is the “hermeneutics of similarity”.
The phrase sounds more forbidding than the idea. A dream presents one thing, but means another. To decipher it, the interpreter identifies the important images, looks for a resemblance between those images and something beyond the dream, then decides that one signifies the other. An eagle becomes Odysseus. Geese become suitors. A violent scene involving birds becomes a prediction of human violence.
In other words, the dream is not read literally. It is read through likeness.
That is what makes Kotwick’s argument extend well beyond the history of superstition. The same mental operation is familiar every time we use figurative language. When someone is described as a rock, no one imagines a piece of stone. We instinctively search for the quality the two things share: solidity, dependability, strength.
For Kotwick, ancient Greek thinkers were grappling with this process centuries before it was formally theorised as metaphor.
Even Aristotle, who approached dreams far more physiologically than many of his predecessors, did not entirely abandon it. He considered dreams to arise from remnants of sensory impressions, which could become altered or distorted during sleep. Yet Kotwick argues that his thinking still preserved the older interest in resemblance. The skilled interpreter was the person capable of recognising similarities between the strange image presented by a dream and whatever lay behind it.
This complicates the neat modern division between rational philosophy and ancient belief. Dreams were not confined to temples, omens or supernatural prediction. They became questions for philosophers, physicians and writers, each attempting to work out why the sleeping mind appeared to speak indirectly.
Medicine provides one of the most revealing examples.
In the Hippocratic work On Regimen, dreams could be understood not primarily as messages from the gods, but as messages from the body. The idea was that sleep might reveal physical disturbances before illness became obvious to the waking patient. Modern scholarship describes these dreams as having physiological origins, potentially offering ancient physicians a mediated glimpse into a body they could not directly examine internally.
The underlying logic, however, remained familiar. The body did not necessarily announce its condition plainly. It communicated through images that had to be interpreted.
Kotwick sees a similar habit of thought emerging in another remarkable Greek text she has studied closely, the Derveni Papyrus.
Discovered in 1962 near Thessaloniki, the partially charred papyrus has been described by UNESCO as the oldest known European book. The surviving copy dates to around 340 to 320 BC, while the work it contains is considerably older. Part of the text offers an allegorical interpretation of an Orphic poem, treating the apparent story of the gods as something capable of carrying another, more philosophical meaning beneath its surface.
Kotwick, who published a German edition and commentary on the Derveni Papyrus in 2017, sees an important connection between this form of allegorical reading and the techniques used to interpret dreams. By the fifth century BC, readers were not simply asking what a text said. They were asking what it might secretly mean.
That instinct remains remarkably familiar.
We approach poetry expecting images to signify more than themselves. We look for symbols in novels, double meanings in films, motives beneath conversation. Even the expression “reading between the lines” assumes that the most important meaning may not be the one sitting visibly on the page.
Kotwick is not suggesting that ancient Greek dream interpreters single-handedly invented metaphor, nor that their predictions should be treated as science. Her argument is subtler. Dream interpretation gave Greek thinkers a particularly rich problem to solve: how can one thing communicate something else?
Over centuries, the answers became entangled with philosophy, medicine, religion, cosmology and literary criticism. Princeton describes Kotwick’s book as the first book-length study devoted to dream interpretation in classical Greece, presenting it not as an eccentric sideline of ancient thought but as part of the early history of interpretation itself.
There is also something unexpectedly modern in Penelope’s response to her own dream.
She does not simply accept its convenient promise that Odysseus will return and eliminate the men occupying her home. She remains sceptical. In Homer’s famous image, dreams pass through two gates: those from horn may prove true, while those from ivory deceive. Penelope is uncertain which kind has visited her.
More than two and a half millennia later, that uncertainty may be the most recognisable part of the story.
We wake with fragments. A face has become somebody else. A room belongs simultaneously to two different houses. Someone long dead is sitting at the table. The logic makes perfect sense until consciousness returns.
Modern dream science offers very different explanations from those available to Homer or Hippocrates, from memory processing to the unusual associative activity of the sleeping brain. Yet the impulse to wonder whether an apparently irrational image has some relationship to memory, anxiety or experience has hardly disappeared. Kotwick notes that contemporary dream research can still describe dreaming as metaphorical or highly associative, without implying that dreams contain supernatural instructions about the future.
Perhaps that is why the ancient material feels less remote than expected.
The Greeks looked at the strangeness of dreams and concluded that the surface was not necessarily the whole story. From there came a question that survived the world that first asked it: if something appears to mean one thing, what else might it be saying?
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