In metaphysics, this hypothetical library of all mentality is known variously as the Akashic Records, collective unconscious, morphogenetic fields, etc. It can be thought of as the mental equivalent of the physical universe. Whereas the common conception is that thought has no ontological status (existence) of its own, merely an epiphenomenon of a physically-based neurological process, this view adopts the notion that thoughts are the mental equivalent of matter. As such, there is consequently a mental universe (sometimes called the astral plane, dreamtime, etc.) which contains all mental activity of every entity everywhere. Thus one's thoughts actually exist "out there" somewhere and your subjective experience of having a stream of thoughts is really your experience of "moving" through the mental universe. In a dream, perhaps you cease your activities in the physical universe and are set loose to travel through the mental. No wonder you encounter people, places, objects and ideas that happened to you that day, as well as things you have never even imagined before.