I’m not by any means claiming that this integrated unit with a body inherently exists. There is no hard line where the body ends and the rest of the universe begins. But we live our lives pretty much under the impression that the body ends at the skin and that we receive information from the rest of the universe through our sense organs. I believe that we do this because having such a mindset is beneficial to survival and we have thus evolved to have this mindset. But the fact that we have such a mindset doesn’t mean it’s the true state of affairs.
I just went outside and looked at the moon through the trees, and it’s a little windy out. There are various ways to analyze this experience, or “instant of mind”, as you call it. The first, obvious one is that I’m a separate integrated unit looking through trees, which are all separate physical objects, at the moon, which is a separate physical object, and hearing and feeling the wind, which is made up of moving air molecules. Then there is the solipsistic view that there is only my mind, and all these things that seem physical are in my head. But considering the first view there is really no good reason to say that the trees, the moon, and the wind are all separate from me. What is actually happening, physically is that light from the moon and trees interacts with my eyes and sound waves from the wind interacts with my ears and air molecules from the wind hits my skin. Those sensations cause my brain to construct an image of the experience. As such, the moon, trees, and wind all exist within me and are not just external, spacially-removed objects. It could be argued that those things are all actually part of “me”, and that there is really no boundary between “me” and my surroundings.
Another way of looking at it would be that I am just an object, not a subject. That would be the opposite of the solipsistic view. It would imply that I am just there, like a radio receiver. And that any thoughts, feelings, or emotions I might have are just physical, electro-chemical responses.
So there are two extremes. The solipsistic view and the physicalist view. In either of those cases there is no boundary between myself and the world around me. Under the physicalist view consciousness doesn’t mean anything. It’s just an electro-chemical response to stimuli that causes me to do things. Under the solipsistic view, I’m not sure what “consciousness” would even mean. I would be conscious, but I’d be the only conscious entity in the universe. It would be tantamount to placing oneself even above what’s thought of as God, because even God allows other conscious beings within his domain.
A middle view is to make a distinction. Once that distinction is made, and I perceive myself, my body, as an entity, then I don’t have to be just an object anymore. I can also be a subject. And when I perceive myself as an individual entity the rest of the universe comes into its own existence and other conscious beings can exist as well.
So I agree, this idea of being a separate integrated unit is an imputed concept. I’m really not separate and I’m really not integrated. Everything is connected and dependent. Consciousness, too, is dependently arisen. It doesn’t exist all by itself. It has to depend on matter, and it needs a subject, a body to ascribe the consciousness to. It also needs objects, things to be conscious of. It can’t just float around in the air by itself, because it’s dependently arisen, just like everything else.
I’m not saying that it’s “purely” derived from matter, or that there isn’t a level of consciousness higher than that of individual human beings, but that it isn’t some form of fundamental “substance” that underlies existence.