। ॥ १२८ ॥
In plain words
The one who knows everything in waking, dreaming and deep sleep — the presence of the intellect and its thoughts, and their absence — that knower is what you call “I.”
Close to the Sanskrit
This one, who knows everything in the states of waking, dream, and deep sleep -- the presence of the intellect and its modifications, and their absence -- is this 'I'.