This is a very intersting episode, because in conjunction with certain other things that occur at the beginning of
The Knight, & at the end of
The Wizard, it suggests among other things that the Seven Worlds have something very like the New Sun's Corridors of Time, thru which Able, and possibly Michael, have traversed by the end.
Able asks Michael about the strange spectral knight he saw at the ruins of Bluestone Isle after leaving Parka. Able thinks he may have summoned that knight in the fashion he might summon one of the denizens of the lower worlds such as Aelfrice to come pay him homage. Michael responds that Able did not call the ghost knight; rather, the knight had summoned Able. Furthermore, Michael informs Able that there was no one on Bluestone Isle but himself. We might suppose that statement meant the phantom knight was just that, a phantom, and didn't "count" in the current census of Bluestone. This being Gene Wolfe, we might suppose wrongly.
Michael concludes the interview by stating he was en route to Aelfrice to seek "that far-famed knight, Sir Able of the High Heart." Then he sinks into the pool, presumably traversing between the worlds then and there.
(Interestingly, IIRC in the earlier chapter referenced, Art/Able the narrator concluded that the strange knight-figure specifically wished him to drink the water of that place, and vanished, satisfied, when he did so. Was this because the water would help "fix" Able in Mythgartr, rather like eating "fixed" Severian the resurrected aquastor in BNS, and made his new body solid matter? Just an aside thought.)
Beyond here there be spoilers for the ending of
Knight, and
The Wizard.
The livery of the strange knight-figure is described as green, with a device of a black dragon. It was made clear afterwards that these were not the arms of the former lord of Bluestone.
Sir Able, after winning armor and horses from the knight that waylaid him in the inn, had his shield painted over plain green (the color of that knight's arms), and stated that he would wait until after he had done something really significant, even more so than slaying a Frost Giant single-handed, before adopting a device and having it painted on his arms.
Of course at the end and climax of The Knight, Sir Able recovers Eterne, slays Grengarm, and is taken up to Skai. Though IIRC it is never explicitly so stated, one would think this would be an achievement worth commemorating on his arms. Therefore the spectral knight's black dragon on a green field was the heraldry of Sir Able, knight of Skai. Also, recall that when the Valfather appears, near the end of The Wizard , he addresses Sir Able as "Drakenritter," lending more support to the theory Able adopted the dragon as his device and heraldry.
The conclusion is inescapable: Sir Able, knight in the service of the Valfather in Skai, slayer of Grengarm, (I note the knight's sword is not described) appeared on the isle in his own past, to summon himself from his interview with Parka, and to send him on the next stage of his strange new life's journey.
Now, it gets even better. Michael has said he is on his way to Aelfrice to seek Sir Able, even though he is speaking to Sir Able at the time. At the end of The Wizard, after Sir Able Drakenritter has abandoned both Skai and Mythgartr to dwell in Aelfrice, after making Disiri a real woman, the book ends with Able stating that Michael has come to invite him into the service of his own lord, by which I presume he means the God of the Highest World. So, either Able went back in time, or Michael descended v-e-r-y slowly thru the pool into Aelfrice so that he only arrives to seek Sir Able after Able had been there for some time.
So, do the Seven Worlds also include something like the Corridors of Time in their design?
Of course, there's much more here that touches on "Able's" exact situation and status in the whole story, on which I might start a new thread or two.
