Qoph, Hebrew letter meaning "back of the head"
Daath, the mysterious, invisible Sephirah, which is never marked upon the Tree, is
associated in the Western svstem with the nape of the neck, the point where the spine meets the skull, the spot at which the development of the brain from the notochord took place in our primeval ancestors.
Daath is usually held to represent the consciousness of another dimension, or the consciousness of another level or plane; it essentially represents the idea of change of key.
-Dion Fortune, The Mystical Qabalah