A short selection from Essay Thirty-three in Darwin, Dogen, and the Extremophile Choice.
… though commoners have no method of ‘beating the cart’ … on the way of the Buddha … this is the very eye of study … it should not be equivalent to ‘beating the ox’ —Dogen 
If you have any doubts about the importance of your body-sense in shaping what ‘appears in the mind’, try the following exercise. Be warned: you must sacrifice a little sleep as you momentarily re-awaken from sleep’s onset to identify the very first image that passes before your closed eyes just before you let go of volition. I’m talking about something so early on in the progression that, in its lack of detail, it’s really more outline-figure than picture—an image that arises even before the first twitch of the shoulders, or the first catch and release of breath due to relaxation of the lips or nasal passage. If you’re like me, you will consistently find that the ‘picture’ accompanying this release of tension reflects the very posture of that body lying in your bed. You might identify this shape with something other than your body—in fact you probably will—but, what does the fundamental ‘contour’ look like?
Do we have here the realignment of efferent muscle impulses (as they disengage from the tensions of covert activity) with playful doodling direct from the visual cortex? I don’t know. But to give you an idea of how deceptive these sleep-onset body images can be, I will describe one of my more recent experiences: I was resting on my back, and just as the tension let go, in my mind’s ‘eye’ I seemed to be looking down at a tiger’s pelt. It was a close-up view, so I could see only two wide black stripes on the orange fur—one narrowing in from the right, and another, lower down, narrowing in from the left. I can’t say whether these colours were ‘real’ or perhaps some trick of certain muscle potentials (adjusting my pupillary-openings, or my relaxation-response, to temperature associations?) that I’ve associated with colours.6 When I reawakened (just barely—it doesn’t take much when you know what to expect), I found my right arm was folded across my chest above my left arm. The left arm was folded across my belly.
I could have sworn it was a tiger I was looking down on!
Something strange happened to the human animal long ago, on the coast or on the plains of Africa, or perhaps on its journeys beyond the Levant. I’m pretty sure other animals don’t divide themselves so,  but their fears and their wants come and go directly, with the appearance and disappearance of unmediated sensations and memories. Their witness and their response are one continuous piece. Still, that they can’t separate them—not by symbolic displacement anyway—doesn’t make their witness-response less real. Indeed, their lives are always Real, while we have to work at it.
1. Dogen zenji, Eihei. 2010 in Bielefeldt, trans., Treasury of the Eye of the True Dharma [Shobogenzo] Book 12: Lancet of Zazen (Zazen shin). Soto Zen Text Project, Online Translations. p. 5/11.
2. de Waal (2016, chapter 3, sub-heading “Redefining Man”, e-book location 1395) points out that the great apes, unlike other primates, appear to use “a representational mental strategy, which allows solutions before action.” Their numbers in the wild have certainly been reduced by human ‘competitive exclusion’, but we might even invoke the multiregional hypothesis (See note 7, essay thirty, and note 2, essay thirty-six.) as we do not interbreed.