That Which Knows
The Key to Liberation by Venerable Ajahn Chah
“Thus the Buddha taught to abide as ‘that which knows’  and simply bear witness to that which arises. Once you have trained your awareness to abide as ‘that which knows’, and have investigated the mind and developed insight into the truth about the mind and mental factors, you’ll see the mind as anatta (not-self).”
This dovetails perfectly with what I’ve been reading in Leap of Perception by Penney Peirce. She talks about learning to not live so much in your left brain. She talks about knowing on different levels and by different parts of our brains. The left brain is logical, rational, and linear. There is nothing wrong with using your left brain, but overdependence on it will skew your judgment and stop your intuition dead in its tracks.
To notice what is going on in your body and environment is to switch to your right brain. I believe our left brain is part of our self, but not the only part or even the most important part. Over-identifying with it is part of what is destroying society: non-holistic, opinion-as-truth, unfeeling, and disbelief in the unmeasurable are characteristics of this single-faceted mind-set.