McLuhan on structure of metaphor

When these questions had been considered with regard to dozens of media and technologies, there came a surprising discovery, namely that all the extensions of man, verbal or non-verbal, hardware or software, are essentially metaphoric in structure, and that they are in the plenary sense linguistic, a fact long accepted by the Bambara and the Dogon tribes, among many others. A "metaphor" means literally "carrying across" from Greek metaferein and was translated into Latin as "translatio." In a word, metaphor is a kind of bridging process, a way of getting from one kind of experience to another. This reaching out always involves a resonating interval rather than a mere connection. When a wag said, "Man's reach must exceed his grasp or what's a metaphor?" he was "right on." Each "side" of the resonating interval is an area of "touch," and in the sensory experience of "touch" there is never a connection but always a gap or an interval. Between the wheel and the axle, the interval (and not the connection) is "where the action is." That is to say, there is a large acoustic factor in touch and in metaphor alike — the audile-tactile.

From a structural "point of view" a metaphor has four terms which are discontinuous, yet in ratio to one another. Aristotle pointed this out in his De Anima (Book III, Chapter VIII):

It follows that the soul is analogous to the hand; for as the hand is a tool of tools, so the mind is the form of forms and sense the form of sensible things.

A four-part analogy is afigure-ground structure. (In a metaphor there are two figures and two grounds in ratio to one another.) Apropos the four-part structure which relates to all human artifacts (verbal and non-verbal), their existence is certainly not deliberate or intentional. Rather, they are a testimony to the fact that the mind of man is structurally inherent in all human artifacts and hypotheses whatever. Whether these ratios are also present in the structure of the "natural" world raises an entirely separate question. It is perhaps relevant to point out that the Greeks made no entelechies or studies of the effects of man-made technology, but only of what they considered the objects of the natural world.