Experience has shown me that the word “self” is most pragmatically defined as the whole of the body, heart, and mind, from head to toe, every cell included, every system running, every conscious and unconscious process, operating as a complete human being.
What goes on in the head is the creation of a “virtual self.” The internal word narrative in the brain, the images of memory and imagination, the sensations of emotions, are the brain’s creation of a virtual self to represent the whole self.
Even though it feels solid, it is not actually the whole self from head to toe. It is a representation. It is a apart of, not apart from, and not the whole. The whole is the complete body, heart, and mind.
The “unit of human existence” in this universe is the whole of the body, heart, and mind, not just anyone of its many parts.