In Greek mythology, dreams were sometimes personified as Oneiros (Dream) or Oneiroi (Dreams). In the Iliad of Homer, Zeus sends Oneiros to appear to Agamemnon in a dream, while in Hesiod's Theogony, the Oneiroi are the sons of Nyx (Night), and brother of Hypnos (Sleep).
For the ancient Greeks, dreams were not generally personified. However a few instances of the personification of dreams, some perhaps solely poetic, can be found in ancient Greek sources.
In Homer's Iliad, Zeus decides to send a "baleful dream" to Agamemnon, the commander of the Greek army during the Trojan War. Oneiros is summoned by Zeus, and ordered to go to the camp of the Greeks at Troy and deliver a message from Zeus urging him to battle. Oneiros goes quickly to Agamemnon's tent, and finding him asleep, stands above Agamemnon's head, and taking the shape of Nestor, a trusted counselor to Agamemnon, Oneiros speaks to Agamenon, as Zeus had instructed him.
The Odyssey locates a "land of dreams" past the streams of Oceanus, close to Asphodel Meadows, where the spirits of the dead reside. In another passage of the Odyssey, truthful dreams are said to come through a gate made of horn, while deceitful dreams come through a gate of made of ivory (see Gates of horn and ivory).
Hesiod in his genealogical poem the Theogony, makes the "tribe of Dreams" (φῦλον Ὀνείρων), among the many offspring of Nyx (Night), without father. Their siblings include: Moros (Doom), Ker (Destiny), Thanatos (Death), Hypnos (Sleep), Momus (Blame), Oizys (Pain), Keres (Destinies), Nemesis (Retribution), Eris (Discord) and other abstract personifications.
Related figures are the Somnia (Dreams), the thousand sons that the Latin poet Ovid gave to Somnus (Sleep), who appear in dreams. Ovid named three of the sons of Somnus: Morpheus, who appears in human guise, Icelos / Phobetor, who appears as beasts, and Phantasos, who appears as inanimate objects.
- Grimal, s.v. Oneiros, p. 328; Smith, s.v. Oneiros; LSJ, s.v. ὄνειρος.
- Grimal, s.v. Oneiros, p. 328.
- Homer, Iliad 2.4–22.
- Homer, Odyssey 24.11–14.
- Homer, Odyssey 19.559–567.
- Hesiod, Theogony 211–225. The translations of the names used are those given by Caldwell, p. 6, table 5. Compare with Hyginus, Fabulae Theogony 1, which makes Dreams the offspring of Night and Darkness.
- Euripides, Hecuba 70–72.
- Pausanias, 2.10.2.
- Ovid, Metamorphoses 11.633–643.
- Caldwell, Richard, Hesiod's Theogony, Focus Publishing/R. Pullins Company (June 1, 1987). ISBN 978-0-941051-00-2.
- Euripides, Hecuba, translated by David Kovacs in Euripides: Children of Heracles. Hippolytus. Andromache. Hecuba. Edited and translated by David Kovacs. Loeb Classical Library No. 484. Cambridge, Massachusetts: Harvard University Press, 1995. ISBN 978-0-674-99533-8. Online version at Harvard University Press.
- Grimal, Pierre, The Dictionary of Classical Mythology, Wiley-Blackwell, 1996, ISBN 9780631201021.
- Hesiod, Theogony, in The Homeric Hymns and Homerica with an English Translation by Hugh G. Evelyn-White, Cambridge, Massachusetts., Harvard University Press; London, William Heinemann Ltd. 1914. Online version at the Perseus Digital Library.
- Homer, The Iliad with an English Translation by A.T. Murray, Ph.D. in two volumes. Cambridge, MA., Harvard University Press; London, William Heinemann, Ltd. 1924. Online version at the Perseus Digital Library.
- Homer, The Odyssey with an English Translation by A.T. Murray, PH.D. in two volumes. Cambridge, MA., Harvard University Press; London, William Heinemann, Ltd. 1919. Online version at the Perseus Digital Library.
- Hyginus, Gaius Julius, Fabulae in Apollodorus' Library and Hyginus' Fabuae: Two Handbooks of Greek Mythology, Translated, with Introductions by R. Scott Smith and Stephen M. Trzaskoma, Hackett Publishing Company, 2007. ISBN 978-0-87220-821-6.
- Ovid. Metamorphoses, Volume II: Books 9-15. Translated by Frank Justus Miller. Revised by G. P. Goold. Loeb Classical Library No. 43. Cambridge, Massachusetts: Harvard University Press, 1916. Online version at Harvard University Press.
- Pausanias, Pausanias Description of Greece with an English Translation by W.H.S. Jones, Litt.D., and H.A. Ormerod, M.A., in 4 Volumes. Cambridge, MA, Harvard University Press; London, William Heinemann Ltd. 1918. Online version at the Perseus Digital Library.
- Smith, William; Dictionary of Greek and Roman Biography and Mythology, London (1867). Online version at the Perseus Digital Library