I had always assumed the Edge of All to be of a more figurative existance than anything else; the idea that at some point, one must pass a threshold and enter the realm of the dark. The journal writer refers to the Mad Journeyman's rantings as mere "theories," but something from death's dream kingdom has obviously driven him into his mad state, and thus one becomes slightly unnerved by the thought of what might possibly lie beyond. Although, I'd disagree with Mr. Mad Journeyman, and say that one would go down instead of east... The W'rkncacnter were ató! Oh, ahem, excuse me.
At any rate, this is but one of Bungie's many allusions to T.S. Eliot's poem, "The Hollow Men." In fact, the whole Myth series, to me, seems to be a literal enactment of this poem, if only portraying the hopeless battle of light vs. dark. Eliot hits it pretty closely: two opposing concepts in juxtaposition to result in "The Shadow." Well, whatever.
If that made any sense, feel free to reply/correct/obliterate. If not, blame psilocybin.
mad jabbo