That which you are cannot be seen or heard or touched or tasted or smelt. Yet every thought shines in its light, you cannot speak of it. It is beyond the three universes of waking, dreaming, deep sleep. If sensations come, don't be agitated, just note that's the first aspect - if thoughts and emotions come, questions come, feelings come,. That's just your second aspect. If nothing comes of blankness or tiredness, restfulness, that's just your third aspect. All of them come and disappear and disappear in the light which you are, the thorium. You can't catch hold of it. Don't even try to think of it, it cannot
Swami Sarvapriyananda teaches one of the shortest and most profound upanishads accompanied by Gaudapada's Karika. This lecture covers Mantra 7 (Part 2).