It's always an uphill battle defending the greatness of Hart Crane. The attacks come in a steady, evenhanded critical stream over the decades.
He has many weaknesses, yes. But he's a great American poet because, to put it in a nutshell, he unites his music (melopoeia) and his imagery (phanopoeia), with an ecstatic-visionary quality (culminating in the concluding section of The Bridge (Atlantis).
Crane's "visionariness" is not like Pound's conservative/archaic mythologizing. Nor like Eliot's resignation/spiritual renunciation. It has, rather, a kind of "titanic" quality, which seems distinctly American - perhaps because it stems directly from Whitman. (Whitman got it from Emerson, & amplified/electrified it. Whitman is to Emerson as Bob Dylan is to the New England folkies.)
As I see it, this American "titanic/ecstatic" visionariness is not simple and pure : it contains a certain ambiguity. "Atlantis", according to the myth, was a high-tech civilization which fell, eons ago, through its own pride & corruption. Crane opens The Bridge with an epigraph from the Book of Job (something like "walking to & fro upon the Earth"), which was spoken by Satan.
The ambiguity I'm talking about stands at the core of that prophetic/apocalyptic mentality in which the poet/prophet, situated between Iron & Golden Ages, looks beyond the conditions of the present into a completely transformed future. One could diagram the situation like this :
[ Titanic-Atlantean high civilization / Present Age / Franciscan-Edenic future ]
- with the poet's vision wavering between, or blending together, all three "ages".
In both Judaism & Christianity, the path from present to future (from earth to kingdom of heaven, or from "this world" to the "world-to-come") goes through redemption and then resurrection (into a new form of angelic or heavenly "body").
The question of how such ideas are to be translated into personal life, and into history in general, has been answered in very different ways. But the visionariness I'm talking about ultimately stems, it seems to me, from an underlying awareness of some kind of crisis or disjunction - between "this world" and "paradise", or between the vicissitudes of mortal life and some kind of different, angelic realm (the pupa/coccoon/butterfly effect).