When someone tells us, and in this case the Buddha did it first, that every little particle of us contains the entire universe, is absolutely right, because without the entire universe there would be no sun, there would be no stars, there would be no chicken cutlets, there would not be all those things that we drink and eat to keep us alive. Everything needs everything to be what it is, and at this point of consciousness we have the expansion of our being.
When the universe itself, or simply our galaxy - just to remain small - is within our field of consciousness, it is us; our galaxy is already within our field of consciousness. Now that you are reading, I'm perfectly within your field of consciousness, and part of you, and you are perfectly within my field of consciousness and part of me. Anything, just the instant we are aware of it, is part of us, and we are part of it, and without consciousness there would be no such things. Had I not awareness that here is this article, this article would not exist, as many things of which we have at the moment no conscience at all; they apparently do not exist, but exist.
The universe is filled with an infinite number of things that at the moment we do not know because we have not seen them yet; they have not taken shape in our state of consciousness, though this does not exclude that they are present in a different domain. We can perfectly define them as dark matter, or potential energy. This universe is composed of dark matter, which is only vibration, the primal one. It is just pure consciousness that hasn't yet taken shape to be manifested. It didn't yet took a spirit and a specific presence, which in the end brings out what I am, what you are, and what each of the existing is. The endless sky is the endless sky, and is part of our being.
If we want to nurture that side of our consciousness which is cosmic, we do not need to take solid or emotional or mental food, it is consciousness itself that nourishes consciousness when it expands to the point of grasping what existence is in a cosmic sense. It is so for every little thing, from the microcosm to the macrocosm.
Consciousness is what gives life to all that exists. When talking about spiritual light, that light is not the electric one, or the one of the stars, or any kind of light that has to do with photonic waves; the spiritual light is a metaphor to define consciousness itself, without which we would not be able to define what is.