I consider this hand mine because I can control it and sense it. If I hold a tennis racket while playing tennis, I consider the racket part of me because I can control it and sense it, and I move it as though it were part of me. If had had no sense or power over my hand it would not be part of me but a mere thing attached to me, like a rope dangling from my clothes is not part of me. If I removed all of the control and sense from every part of my body, what would be left? My mind, for I have control of and sense of my thoughts. What I removed control and sense of my thoughts? Then there would be nothing. There would be no me. No sense of self.
Consciousness is therefore a variable and is proportional to the systems which are sensed and under control.