The Great Epic of the Bhārata dynasty 12.209.16

12.209.16

evaṃ hi tapasā yuktamarkavattamasaḥ param |
trailokyaprakṛtirdehī tapasā taṃ maheśvaram || 16 ||

This is due to the nature of the Soul. The Soul should be comprehended. All the elements and the objects they compose exist in the Soul. In the state called dreamless slumber (sushupti), the manifest human body which, of course, is the door of dreams, disappears in the mind. Occupying the body the mind enters the soul which is manifest and upon which all existent and non-existent things depend, and becomes transformed into a wakeful witness with certainty of apprehension. Thus dwelling in pure Consciousness which is the soul of all things; it is regarded by the learned as transcending both Consciousness and all things in the universe. That yogin who in consequence of desire covets any of the divine attributes (of Knowledge or Renunciation, etc.) should regard a pure mind to be identical with the object of his desire. All things rest in a pure mind or soul. This is the result attained to by one who is engaged in penances. That yogin, however, who has crossed Darkness or ignorance, becomes possessed of transcending effulgence. When darkness or ignorance has been transcended, the embodied Soul becomes Supreme Brahma, the cause of the universe. The deities have penances and Vedic rites. Darkness (or pride and cruelty), which is destructive of the former, has been adopted by the Asuras. This, viz., Brahma, which has been said to have Knowledge only for its attribute, is difficult of attainment by either the deities or the Asuras.