Barfield disputes the modern received view that mind accrues “epigenetically” from the brain once it reaches a certain level of anatomical complexity. Under such a view we can have a “thinking determined by the brain only.” Such a view forces us to conceive of man as “a brain on legs” (Worlds Apart 195 & 231). In contradistinction, Barfield contends that once the whole body thought. “Consciousness,” he reminds us in an essay on ‘Language and the Evolution of Consciousness,’ “resembles a spark located within the brain much less than it resembles a diffused light focused into the whole body from without”.

The mind is, rather, the result of the internalization process and the descent of the potency into the human body. The mind’s interior was once anterior. Anthroposophy‘s theory of brain and mind—articulated here by Sanderson in Worlds Apart—informs all of Barfield’s own thinking:

[Man] has his brain, for his waking life, swelled out into a bubble in his head, but radiating in the form of nerves through the whole organism. In all this, but especially in his head, he can be psychically active, because he is physically passive. He has, at the other pole, his motor organism—limbs and metabolism—which also reaches up into the head, in the form and function of mouth and lower jaw. And between the two poles his heart and chest, his breathing and his blood circulation—which also permeate the whole body, but are focused in his heart and lungs.

We say that, when he is asleep—and also, even during the day, in his unconscious, from which his impulses of will spring so unaccountably—his relation to the spirit is still that of the first period [of the evolution of consciousness, or original participation]. In his dreaming, and, in the half-conscious goings-on of his emotional life, he is still really living in the second period [that of the intellectual soul]. It is only when he is wide-awake, and actually thinking and perceiving that he is wholly up to date.
(World’s Apart 196)

Barfield dismisses the epigenetic approach to brain/mind that arises under the sway of the brain-physical conception as logically indefensible:

In so far as you insist on talking about the brain instead of the mind… the series of brains, observing and observed, is rather like the procession of oozlem birds. Each bird consumes the one behind it. But how do you deal with the last bird in the procession, or how does it deal with itself?

…if you start from the brain and say it “constructs” the world it is aware of, you seem to leave out of account the fact that the brain as an object of observation is itself part of a world which you yourself have constructed. Surely you have got to start with the art of construction and not with the brain!
(Worlds Apart 56)

Brain-physical thinking fails to account for the very self-referentiality that makes the hypothesis of the brain-physical possible in the first place, as Barfield, his impatience apparent, demonstrates:

You may go on gabbling . . . words like supernaturalism, dualism, psychosomatic (and I have no quarrel with that word, properly used), input, feedback, output and the rest of it, till you are black in the face. You may, for all I know, succeed in detecting a physical or electrical charge in the brain for the airiest fragment of a frolic of a half-thought that ever hovered for an instant in the fancy of Mercutio. But you can never, without talking nonsense, obliterate the ultimate cleavage between (a) consciousness itself and (b) that of which it is conscious.
(Worlds Apart 41-42; Hunter is speaking)