In the Sophist, Plato turns to the mythical battle between the gods and giants to portray his vision of ontology as essentially plural: ontology as ontologies:

What we shall see is something like a battle of gods and giants going on between them over their quarrel about reality [gigantomachia peri tes ousias] (…)
One party [the giants] is trying to drag everything down to earth out of heaven and the unseen, literally grasping rocks and trees in their hands, for they lay hold upon every stock and stone and strenuously affirm that real existence belongs only to that which can be handled and offers resistance to the touch. They define reality as the same thing as body, and as soon as one of the opposite party asserts that anything without a body is real, they are utterly contemptuous and will not listen to another word. (…)
Their adversaries [the gods] are very wary in defending their position somewhere in the heights of the unseen, maintaining with all their force that true reality consists in certain intelligible and bodiless forms. In the clash of argument they shatter and pulverize those bodies which their opponents wield, and what those others allege to be true reality they call, not real being, but a sort of moving process of becoming. On this issue an interminable battle is always going on between the two camps. (…)
It seems that only one course is open to the philosopher who values knowledge and truth above all else. He must refuse to accept from the champions of the forms [the gods] the doctrine that all reality is changeless, and he must turn a deaf ear to the other party [the giants] who represent reality as everywhere changing. Like a child begging for ‘both’, he must declare that reality or the sum of things is both at once.
(Sophist 246a-249c, emphasis added)

The mythical tale of a war between generations of divine beings was ancient even in Plato’s time.¹ This battle (Gk machia) is gigantic, not only because it is waged on one side² by the giants (Gk gigantes), but also, according to Plato, because it takes place peri tes ousias — as a war concerning the nature of reality (Gk ousia³) waged between primordial powers of Being that are all gigantic exactly as ontologies. Each of them has universal claim.⁴ Each claims to be “real existence” or “true reality” or “real being” or “the sum of things” (as Plato variously expresses the point). And where a war is waged between gigantic powers over gigantic issues, that war is of course also gigantic.

This war is never-ending (“always going on”, as Plato notes) since no one of these powers can ever defeat its rivals: they are all equally fundamental, equally original and equally powerful. Such equality is the condition of the powers persisting in Being as a plurality since, if there were any difference in their power, Being would ultimately be singular. Its weaker forms would not be able to hold out forever against the stronger. (Or, inversely, when they are able to hold out forever, they cannot be weaker.) Further, ontological plurality (hence ontological equality) is the condition of the difference between Being and beings as its ground: beings can be different from Being and yet remain in Being exactly and only because plural Being is different in and from itself. Absent such differentiating-uniting power in Being itself, beings could not come to be nor maintain themselves in being. Deeper than them is the gigantic power to be in difference. Take Today 22 expresses this notion as “the fact that dialogue as a process of creating the new came before”.

The three ontologies envisioned by Plato (each original and originating)  are materialism (aka only what can be touched is real aka the giants), idealism (only what can be conceived is real aka the gods) and both of these together (as held by the childish philosopher or philosophical child). The third is necessary if Being is plural (and not just a lifeless One). But the first and second are equally necessary if the third is their combination or “dialogue”.

McLuhan’s project in one sense was to reprise these points aka (in Whitehead’s phrase) to mount, yet again, “a series of footnotes to Plato”.

Here he submits that Being is plural, that it entails contesting “universal forms of experience” and that this contest of “universal forms” is synchronic and “now”:

One of the amazing things about electric technology is that it retrieves the most primal, the most ancient forms of awareness as contemporary. There is no more “past” under electric culture: every “past” is now. And there is no future: it is already here. You cannot any longer speak geographically or ideologically in one simple time or place. Now, today, we are dealing with universal forms of experience. (‘Electric Consciousness and the Church’, 1970)⁵

Again:

Every medium is in some sense a universal pressing towards maximal realization.” (‘Notes on the Media as Art Forms’, Expl 2, 1954)

Here he characterizes the contest of “universal forms” (often styled “environments” by McLuhan) as a “war” between “worlds” in which a third form (“a two-way bridge”) is also at work:

There does exist, then, a two-way bridge between the traditional and technological worlds which are at war in Western culture. But it has been officially ignored or condemned. To travel this bridge requires of the traveller an acquaintance with the language and techniques of poetry [aka the ear world] on the one hand, and of the language and techniques of painting, architecture, and the visual world [aka the eye world] on the other. Few are prepared to acquire both languages and so the war between these worlds continues, waged witlessly in classroom and market-place alike (‘Space, Time, and Poetry’, Explorations 4, 1955)

Here he defines the three “universal forms” in the same terms as Plato, the “idealists”, the “practical men” and “dialogue”:

The idealists share with the experienced and practical men of their time the infirmity of substituting concepts for percepts. Both concentrate on a clash between past experience and future goals that blacks out the usual but hidden processes of the present. Both ignore the fact that dialogue as a process of creating the new came before (Take Today 22)

The “practical men of their time” are those entrepreneurial “giants” who “drag everything down to earth out of heaven” and who “strenuously affirm that real existence belongs only to that which can be handled” or otherwise managed⁶. “They define reality as the same thing as body, and as soon as one of the opposite party asserts that anything without a body is real, they are utterly contemptuous and will not listen to another word.” The “idealists” or “Peter Pans“, in contrast, “are very wary in defending their position somewhere in the heights” of their ivory towers. Opposed to both, but in such a way as to unite them (as its name implies), is the third position of “dia-logue” holding that “reality or the sum of things is both at once”.

That this war “is always going on”, that “all is always now” (as Eliot has it⁷) is nicely captured by McLuhan in the title of a 1944 talk (published in 1946 and then reprinted as the concluding chapter of The Interior Landscape in 1969): ‘An Ancient Quarrel in Modern America’.

The knot of times, plural, implicated in this vision of the contemporary gigantomachia peri tes ousias, right here, right now, the most ancient and the immediately modern together, is treated extensively by McLuhan:

time considered as sequential (left hemisphere) is figure and time considered as simultaneous (right hemisphere) is ground. (GV 10)

we live in post-history in the sense that all pasts that ever were are now present to our consciousness and that all the futures that will be are here now. In that sense we are post-history and timeless. Instant awareness of all the varieties of human expression constitutes the sort of mythic type of consciousness of ‘once-upon-a-timeness’ which means all time, out of time. (‘Electric Consciousness and the Church’, The Medium and the Light, 88)

And over and over again he cited Eliot’s definition of the “auditory imagination” which “fuses the old and obliterated, and the trite, the current, and the new and the surprising, the most ancient and the most civilized mentality”.⁸

McLuhan expressed this complicated “fusion” in many ways — the intercommunication of the old and new, but also the interrelation of the eye and the ear, or the “doubleness” of “the written and oral traditions”:    

Plato and Aristotle, the representatives of the new literate culture of Greece in philosophy, had this same doubleness. They straddled the written and oral traditions. They translated the tribal encyclopedia of the preceding culture into the written, classified form…⁹

Always at stake was the fundament — or fundaments — of Plato’s gigantomachia.