One pair of gates is made of horn, and one of ivory. Those of the dreams which issue through the gate of sawn ivory, these are deceptive dreams, their message is never accomplished.
Penelope articulates the classical dream-gate opposition in which ivory is the material of false, unaccomplished visions, establishing the foundational depth-psychological association of ivory with beautiful illusion and deceptive unconscious content.
, Odyssey of Homer, 2009thesis