Like I said before, now it's really tough for me to read books that reflect pre-scientific understanding of the human mind.
Or to seriously consider any form of spirituality/meditation/philosophy that doesn't address what Robert Burton, M.D. says in the opening pages of his "A Skeptic's Guide to the Mind: What Neuroscience Can and Cannot Tell Us About Ourselves."
Our brains possess involuntary mechanisms that make unbiased thought impossible yet create the illusion that we are rational creatures capable of fully understanding the mind created by those same mechanisms.
Our brains have evolved piecemeal; contradictions, inconsistency, and paradox are hardwired into our cognitive machinery.
We are hardwired to experience unjustified feelings about ourselves, our thoughts, and our actions; we possess an irrepressible curiosity and desire to understand how the world works; we have developed an uncanny ability to see patterns whether or not they exist outside of our perceptions.
...For neuroscientists and philosophers, as with the rest of us, the visceral feeling of knowing you are right is far more convincing than the thought that we have limits to our powers of reason.
...At the purely intellectual level, even the most science-impaired among us understand that mental states, no matter how seemingly psychological in origin, ultimately arise out of brain states. Everything we experience is generated by mindless brain cells and synapses.
Nevertheless, we cannot shake the contrary feeling that there is a personal "I" that is sufficiently separate from these states to have an understanding of this proposition.
Pay special attention to that last sentence from Burton.
This applies not only to the everyday sense of me-ness, but to the almost ubiquitous religious belief in a soul or some other form of non-material consciousness separate from the goings-on in the brain.
Burton says that he, along with everyone else, has a feeling of a special "I" that is both writing and reading the sentence being composed. I have that same feeling as I write this blog post. Yet that feeling is generated by the brain which is doing a hell of a lot of unseen, unknown work behind the scenes of conscious awareness.
The spatial qualities of the experience of a mind arise from subconscious brain mechanisms. Our thoughts about the dimensions of mind aren't similarly constrained by our biology. Conceptually, the mind can be anything that we imagine.
Which explains the amazing imaginative quality of the world's holy books, mystical teachings, New Age fantasizing, blue sky philosophizing, and such. We can imagine anything. But imagination doesn't tell us how the brain is producing those imaginings.
Similarly, we aren't aware of how we are aware of sensory perceptions such as seeing things. This allows people to blather on in books about Buddhism and non-duality (among others) about "pure perception" lacking any cognitive component that could veil the reality of what is simply there.
Not true. Burton's speaks of seeing the flight of a moving Frisbee.
There is nothing in the retinal signal that can distinguish between the perception of the image moving as a result of eye movement or actual movement of the object in the external world.
What your eyes see is insufficient to determine whether a Frisbee is zipping by at high speed, or is actually hovering motionless in front of you, with the illusion of the Frisbee's movement being created by your rapidly scanning eyes.
It's only by having past knowledge of what a Frisbee flight path looks like and the knowledge that you are out playing Frisbee with a friend that allows you to unequivocally "see" the Frisbee in flight.
This visual perception is made by the brain, not the eye, and is the result of the brain using both visual input and prior knowledge to calculate the likelihood that the Frisbee is actually in motion. (A similar visual ambiguity occurs when you try to decide whether it's your train or the train on an adjacent track that is pulling out of the station.)
Bottom line, given our inability to intuitively understand how the brain produces conscious awareness:
There is no alternative to the scientific method for studying the physical world.