Shri Krishna goes in depth into the nature of self, starting with the explanation of Cit and Acit.
All living entities are manifested using God’s two energies, soul energy, and Maya, the material energy or matter. Matter by itself is lifeless and needs a soul to come alive and the soul needs a body to experience material energy. Thus, both come together to form a living being. Krishna calls these cit (consciousness) and acit (matter). Krishna says that In the universe, you cannot find anything which is outside of these two.
This is Sankarācārya's commentary upon this verse. God in Vedanta is that Reality which is the cause of this universe through its double nature, aparā and parā. These two aspects of the Divine constitute the cause of the universe. That is why, in the Upaniṣads, they often mention creation as, 'the Lord projected this world and entered into it and remained there, like a spider that creates its web out of itself and lives in that web.'
Please pay attention to the example used of a spider. A key point to be noted is that a spider creates the web but never gets stuck in its own web. Just like that, God has created maya but never gets impacted by it.
The concept of Higher and lower nature, intertwined with each other, is responsible for the diverse manifestations we see in the world. Think of it like this: without matter, the hidden energy in the Spirit wouldn't have a place to show itself. And matter, being lifeless on its own, needs the Spirit to bring it to life. It's like electricity and a light bulb. Electricity needs the bulb to shine as light, and the bulb needs electricity to light up. The bulb is the tool through which electricity becomes light. In the same way, the Spirit, working through the five layers of matter, finds a way to express its power.