Here is McLuhan’s mentor at the university of Manitoba, Rupert Lodge, at the beginning of his ‘Comparative Method in Philosophy’:¹

Human knowledge is the product of two factors, sensation and intelligence. From sensation we derive the ultimate constituents of experience, its elementary qualities, its reds and blues, louds and softs, roughs, smooths, and the rest. These are not invented or originated by us, but are pure discoveries, sought after by us with interest, as gifts from the hand of nature which we may learn to use wisely and with discrimination. From the intellect with its spontaneous demand for unity, order, and system, we derive the formal patterns of logic and mathematics, in terms of which we seek to compare, distinguish. and arrange the sensory content of experience in such elementary relationships as apart or together, before or after, larger or smaller, more or less intense, to the right or to the left of, etc. These two factors are not found in complete isolation from one another, separated as if with a hatchet. In the simplest sensory experience there is at least a minimum of inference, as when we “separate” and “contrast” red and blue and “identify” this or that quality as belonging to the visual or auditory “system”. So, too, intellectual elaboration occurs only on the occasion of some stimulus which is sensory in origin and in its associations. Yet, since they differ in function, the one factor being essentially receptive and the other essentially originative, it is convenient as well as usual to regard them as distinct. While both are present in concrete knowing, each of these factors shows a considerable range of variation. At the one extreme it is possible for the sensory factor so to predominate as completely to overshadow the presence of intellectual factors. (…) At the other extreme it is possible for the intelligence (…) to predominate…

*

McLuhan’s library preserved at the University of Toronto does not have Ogden and Richards’ 1922 Foundations Of Aesthetics, which they co-authored with the painter James Wood. But he would certainly have read it at Cambridge along with its closely related Meaning of Meaning (Ogden and Richards, 1923), which McLuhan’s library has in a first edition copy with his marginal annotations. Given his training with Rupert Lodge at the University of Manitoba, immediately before his studies at Cambridge with Richards, he would have found the discussion of Schiller in the Foundations of great interest. For Lodge’s method, which set the program for McLuhan’s entire career, was a variation on Schiller’s as described in the Aesthetische Briefe of 1794.²

Here are Ogden and Richards on Schiller in The Foundations Of Aesthetics:

it was Kant’s view of the relations of Art and Play which led Schiller in his Briefe Uber die Aesthetische Erziehung der Menschen to elaborate a theory of harmonious activity in which a balance or equipoise is maintained. There are, according to Schiller (Letter 2), two opposing demands in man — that of the sense-impulse, and that of the form-impulse.³ (…) Harmony can be attained without diminution of either. And here the function of Play is introduced. The object of the sense-impulse is life, the object of the form-impulse, shape (Letter 15). The object of the play-impulse, expressed in a general proposition, can then be called living shape, or in its widest signification, Beauty.

Beauty, then (Letter 16), results from the reciprocity of two opposite impulses, and from the union of the opposite principles: we must seek its highest ideal in the most perfect possible equipoise.

“The scales of a balance stand poised”, he proceeds (Letter 20), “when they are empty; but also when they contain equal weights. Thus the mind passes from perception to reflection by an intermediate state (Stimmung) in which sense and reason are active at the same time, but thus mutually destroy their [one-sided] determining power and effect a [potentially positive] negation through an opposition [in which mere opposition is countered by relation] (…) if we call the condition of sensuous determination the physical, and that of reflective determination the logical and moral condition, we must call the condition of real and active [mutual] determinableness [Bestimmbarkeit]⁴ the aesthetic condition.”⁵

Modernity for Schiller, and then for Nietzsche a century later, and the Toronto school a half century later again, is the time when the balanced pans of a scale before a weighing (the precondition of any trustworthy weighing) are perceived as being only empty; and the difference between the two pans is perceived only as an antagonism. The great question posed by them all was how to restore perception, as McLuhan put it over and over again (including to the Ontario Dental Association), that “the gap is where the action is”.

It is here in the precondition of balance, and in the precondition of balance alone, that the play of the Spieltrieb is to be found already at work.