In a cinema show the room is first darkened, artificial light is introduced; only in this light are the pictures projected.
For differentiation a reflected light is thus necessary. A sleeper dreams, he is not out of sleep: only in the darkness or ignorance of sleep can he see the unreal dream objects.
Similarly the darkness of ignorance gives rise to the knowledge of the perceptions of the world.
Ajnana (Ignorance, Darkness) → Avarana (Veiling)
This veiling is a characteristic of ignorance; it is not of the Self: it cannot affect the Self in any manner; it can veil only the jiva.
The ego is insentient: united with the light from the Self, it is called jiva. But the ego and the light cannot be seen distinct from each other; they are always united together. The mixed product is the jiva, the root of all differentiation. All these are spoken of to satisfy the questioners.
Such is the representation of the subtle body. The senses and other organs act separately, whereas the inner organs and the vital airs can work only in unison. Therefore the former are vyashti (individualistic) and the latter are samashti (collective).
Sahasrara (cranium) — Ether = Jnana Kantham (throat) — Air = Mind Hridaya (Heart) — Light = Intellect Nabhi (navel) — Water = Memory Mula (Solar plexus) — Earth = The Ego