Stan K-B [to RSGwynn):  As you point out, all enjambs are not born equal…Dipping at random, I find an (aab) unit followed by an end-stopped (b):
We heard cremationists guffaw and snort
At Grabermann’s denouncing the Retort
As detrimental to the birth of wraiths.
We all avoided criticizing faiths. [623]
Then comes a (ccdde) enjambed-unit burst = role/soul/Chinese/teas/go, followed by (eff) = Poe/strange/range.

RSGwynn: … the Botkin hospital link a little far-fetched, but in Texas, if we say, "He's at Rusk," we mean he's loony.

 

JM: To grab the opportunity presented by Stan’s quotes* and Gwynn’s last comment related to “loonies,” I’d like to return to Shade’s verses (623/629) in connection to which Kinbote notes that above “the fate of beasts” Shade had initially written, and then struck out: “The madman’s fate.”  He was now able to introduce his conjectures about “the ultimate destiny of madmen’s souls,” when he asserts that “personally” he has not “known any lunatics; but …heard of several amusing cases in New Wye (“Even in Arcady am I,” says Dementia, chained to her gray column).”
His favorite case may hide an authorial clue and criticism: “ …the old man…at the Exton railway station, who thought he was God and began redirecting the trains, was technically a loony, but John calls him a fellow poet.” **  (Kinbote/Nabokov, as suggested earlier)

 

 

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*Is the name Grabermann related, from the German,  to “graves and tombs” and to cremationism? Tombs will gain importance with the reference, on CK’s notes to line 629, to the painting by Poussin, indicating death in Arcady, and madness (the inscription read by the shepherds is carved on a tomb).

** CK notes for the lines SKB selected on “enjambs”, that he’s mentioned “a trivial variant” and adds: “the whole passage…would be quite Hudibrastic had its pedestrian verse been one foot shorter” (jambs, feet, pedestrian verses…!)