Sri Aurobindo translates Mandukya Upanishad, Verse 4: “He whose place is the dream, who is wise of the inward, who hath seven limbs, to whom there are nineteen doors, who feeleth and enjoyeth subtle objects, Taijasa, the Inhabitant in Luminous Mind, He is the second.”
The Mandukya Upanishad next describes the dream state of conscious awareness. The description of seven limbs and nineteen doors corresponds to that of the being in the waking state. The dream state works through impressions experienced by the outer being, but also takes up experiences in the subtle being, the vital world and a wider frame of experience in some instances. The dream state corresponds to the twilight in the world, neither the full light of day, nor the deep darkness of night.
The focus of the waking consciousness is on the outer world; the focus of the dream state is on inner states of mental activity. The objects and actions may appear to be solid and real to the dreamer, but they are nevertheless reflections of an inner awareness in the mind, not direct interaction with the outer world through the senses of perception and action. The mind however is not entirely isolated from the outer perceptions which may in fact influence some of the experiences in the dream state; yet they are transformed into an inner view in the mind.
The dream state can also liberate the conscious being from the limitations of the waking state world, and thus, it is possible to explore and participate in the wider vital world and energies, and this represents a method of knowing that goes beyond specific sensory impressions, as the being can travel to distant realms of vital activity and bring back partial or complete knowledge from them.
Sri Aurobindo, The Upanishads, Mandukya Upanishad, pp.319-321