2.1.03
It is this alone, the means, by which one perceives and understands form, taste, smell, sound, touch, and union; and what else remains or persists? This is indeed that.
Bhāṣya 2.1.03
The one who remains awake in all beings when they are asleep is the supreme Brahman. The one who journeys to the womb and beyond is an individual being and not Brahman.
The secret knowledge of Brahman is explained to clarify the distinction between the soul and the Supreme Lord and also to understand how the individual being transforms after death.
The individual being is the one who experiences the results of actions and undergoes states like deep sleep.
The one who remains awake in all beings when they are asleep during cosmic dissolution is Lord Vishnu, the supreme Brahman. The one who journeys to the womb and beyond is an individual being and not Brahman.
Indeed, Brahman is properly known through the distinction between living beings.