The inner chamber of a Greek temple that only specially dedicated priests could enter — literally the not-to-be-entered, from the alpha privative plus the root of entering. Cameron McEwen supplies the term in dialogue 61 as the technical name for the hidden place a liturgy circles, and dialogue 62 arrives at it again from the other end, through the dyt in troglodyte. What makes it more than an antiquarian note is the use it is finally put to: the medium, on Cameron's account, has the adyton's structure, since entering it converts it into an object lit by some further medium. New to it — dialogue 62 carries the full argument; dialogue 61 has the liturgical introduction.
Across the dialogues
Promoted from an image for the sacred to the series' working definition of a medium — reached a second time from the opposite direction, through etymology rather than liturgy, and then spent, so that a term borrowed to describe a temple ends the session carrying the claim that media are structurally unenterable
The definition is kept architectural on purpose — a real room with a real prohibition, which is what lets it later carry an epistemological claim without becoming a metaphor.
"And the adyton was that part of a Greek temple that could not be entered except by priests that had been specially trained and dedicated to that temple. So it was the holy of holies in a Greek temple."
Ninety minutes after the etymology, the term is collected — the space Bob has been calling nebulous, where media effects are supposed to live, is given the temple's name.
"this relates exactly to the adyton. The adyton of the temple is the space that you can't go into."
The prohibition is restated as a structural impossibility rather than a rule — inspection is what destroys the thing inspected, converting a medium into one more object requiring a medium to be seen.
"the medium, you can never go into that space because as soon as you go into that space, you make it into an object, you make it into a pole that itself is illuminated only by its medium. So the medium is inherently dark."
The payoff is exegetical — one of McLuhan's most-repeated and least-explained lines is given a reason rather than an illustration.
"So when McLuhan talks about how the environment can never be seen, ultimately that's what he's talking about. The ultimate environment that makes it possible for humans to have an environment can never be seen, can never be perceived."
Connections
Reached in dialogue 62 through the dyt of troglodyte — cave-enterer against not-to-be-entered.
The space between, which Cameron says Bob has been calling tactility all along.
Offered as what McLuhan means when he says the environment can never be seen.