The Oneiroi are the personified deities of specific types of dreams such as nightmares, sexual dreams, etc. They were thought to dwell on the shores of the Ocean in the extreme west. True dreams issue from a gate of horn, while deceptive dreams issue from a gate of ivory. The most important one is Morpheus, the god of dreams. His brothers are Icelus, Phobetor and Phantasos. At his command, they sent forth the various shapes that appear in the dreams of humans.