Of heaven's meditation, yoking wave
To kneeling wave, one song devoutly binds—
The vernal strophe chimes from deathless strings!
O Thou steeled Cognizance whose leap commits
The agile precincts of the lark's return;
Within whose lariat sweep encinctured sing
In single chrysalis the many twain,—
Of stars Thou art the stitch and stallion glow
And like an organ, Thou, with sound of doom—
Sight, sound and flesh Thou leadest from time's realm
As love strikes clear direction for the helm.
Swift peal of secular light, intrinsic Myth
Whose fell unshadow is death's utter wound,—
O River-throated—iridescently upborne
Through the bright drench and fabric of our veins;
With white escarpments swinging into light,
“Fell” is used here in the archaic sense of “fierce, terrible.” Compare Hamlet’s death speech: 
 …as this fell sergeant, death, / Is strict in his arrest… 
 “Unshadow” is light, but light conceived as the opposite of shadow, a negation of shadow. It is fierce and terrible  toward  death–in fact, it kills death and affirms life. “Utter wound” means a fatal wound (as in the archaic expression “to the utterance”: to the death), but also suggests the uttering of speech, myth, poetry, which (Crane implies) is what slays death. 
 …death, thou shalt die.  –John Donne
Atlantis