Sri Aurobindo
Letters of Sri Aurobindo
Volume I - Part 1
But why do you want to connect these things with the soul? These four names [vaiśvānara, taijasa, prājña, kūṭastha] are given to four conditions of transcendent and universal Brahman or Self,– they are merely conditions of Being and Consciousness – the Self that supports the Waking State or sthūla consciousness, the Self that supports the Dream State or subtle consciousness, the Self that supports the Deep Sleep State or Causal consciousness, kāraṇa, and the Self in the supracosmic consciousness. The individual of course participates, but these are conditions of the Self, not the Self and soul. The meaning of these expressions is fixed in the Mandukya Upanishad.