An Anthroposophical term, used by Barfield as roughly synonymous with Natura Naturans. Originally introduced by Aristotle as a name for a proposed fifth element, etheric designates that non-material aspect of the cosmos and of nature always in the process of becoming which gives form to matter, to the body, to things. According to Barfield, the etheric was once routinely observable.

Etheric forces, Barfield explains in an interview, "are imagination operating in reverse. Whereas imagination uses the spatial to get to the non-spatial, what the organic force is doing is moving out of the non-spatial realm (the creative logos, if you like) to convert it into space--of the immaterial producing a material, spatial world. . . . What the etheric does is, to put it crudely, to convert time into space . . ." (TI 9).

The etheric was once open to experience, as Barfield explains to Shirley Sugerman in another interview:

The Greeks in particular really lived in an experience of [the] etheric. Our thoughts, by comparison with the thoughts the Greeks could have, are really a kind of shadow of the real living thoughts cast by the impact of these living thoughts on the physical brain. We get a sort of after-echo or shadow back from the physical brain of what the real thoughts are. (12)
Once, a "Heraclitus felt the 'ether' in himself because it was still engaged in making him, as it was still making all men, into an individual thinker with a brain-focused mind." Now, however, we are brain-physical: "We are individual thinkers. Our minds are brain-focused. Consequently our relation to it is quite different. We cannot sit still and experience it in ourselves. If we want to experience it, we have to go out into it" (WA 135).
See in particular, Unancestral Voice, passim; Worlds Apart, passim.