The Source "thinks" of the basic creation, that I have labelled the "Real Universe", and there is one Cosmic Consciousness which has as its body the entire creation.
The analogy is used of rays of light from the sun, to describe the Source focusing on a particular part or aspect of the creation and differentiating or particularising itself. I have drawn this as the thick horizontal line. As attention moves to the right, it becomes more focused on the particular and more differentiating. Let me call this line the "line-of-differentiation".
This process of differentiation has been labelled as successive body sheaths, in particular the causal (mental/subtle ideas) and astral (bliss/feeling/light), and finally the physical.
This process may also be related to the central column of the spine, the sushumna, and the chakras along it. The extreme left of the line-of-differentiation is the Heart (not a chakra). The circle representing Cosmic Consciousness is the Sahasrar, causal is the Ajna, astral is the Anahat, and the rightmost end of the line is the Mooladhar chakra. Chakras below the Anahat are lower-astral. You project this cosmic body into your own physical body.
Remember always that EVERYTHING comes out of the "I", and thus everything in your universe has profound symbolism. And is not really different from what it symbolises.
The "I" in the physical body is not different from the Source, except that it is focused on its own projected physical universe.
This personal universe is projected from the "I", thus all content must come from within the "I", even though "other" people are perceived as totally separate entities.
Other entities can only have come from within oneself, so awareness of these people must come from the Cosmic Consciousness where the individual rays originate.
There is really no difference between the "I" and the Source, except for some ideas.
Many non-dualist teachers will insist that there are no "levels" of Self-realisation, however I maintain that there are. Your centre, or "the place from which you are looking" can move to the left along the line-of-differentiation, not necessarily in a single jump from right to left.
The true Gyani has totally killed the mind and rests as the Source and is the Heart of all.