In Greek mythology, the Oneiroi (Ὄνειροι, Dreams) were, according to Hesiod, sons of Nyx (Night), and were brothers of Hypnos (Sleep), Thanatos (Death), Geras (Old Age) and other beings, all produced via parthenogenesis. Cicero follows this tradition, but describes the sons of Nyx as fathered by Erebus (Darkness).
The Latin poet Ovid presents them not as brothers of Hypnos, but as some of his thousand sons. He mentions three by name: Morpheus (who excels in presenting human images), Icelos or Phobetor (who presents images of beasts, birds and serpents), and Phantasos (who presents images of earth, rock, water and wood).
In Homer's Iliad, an Oneiros is pictured as summoned by Zeus, receiving from him spoken instructions, and then going to the camp of the Achaeans and entering the tent of Agamemnon to urge him to warfare.
The Odyssey speaks of the land of dreams as past the streams of Oceanus, close to where the spirits of the dead are led (Hades). Statius pictures the Dreams as attending on slumbering Hypnos (Somnus in Latin) in a cave in that region.
In another passage of the Odyssey, dreams (not personified) are spoken of, by a double play on words, as coming through a gate of horn if true (a play on the Greek words for "horn" and "fulfil") or a gate of ivory if false (a play on the Greek words for "ivory" and "deceive"). For this image and its echoes in later literature, see Gates of horn and ivory.
- Smith, William. Dictionary of Greek and Roman Biography and Mythology.