Doctor Crane, the rational sceptic of Long Sun, brings the validity of Silk's enlightenment by the Outsider into question when he laughingly reduces it to a medical phenomenon:
Crane smiled, and for a moment actually appeared cheerful. 'You had a cerebral accident, that's all. Most likely a tiny vein burst as a result of your exertions during the game. When that happens in the right spot, delusions like yours aren’t all that uncommon. Wernicke's area, it’s called.' He touched his own head to indicate the place. (Lake 494)
Crane takes visible pleasure in "debunking" what he sees as Silk's irrational faith. His medical explanation for a seemingly supernatural event reflects theories that the visions Saint Paul experienced on the road to Damascus were caused by a pre-existing neurological condition. In "St Paul and Temporal Lobe Epilepsy," D. Landsborough speculates that the New Testament accounts of Paul's conversion bear "a close resemblance to the psychic and perceptual experience of a temporal lobe seizure" (659). Wolfe seems to be playing with these speculations, and challenging them, when he presents Crane’s theory, which ultimately fails to explain what Wolfe himself has called a "purely miraculous" event ("The Wolfean Oracle Speaks"). During his enlightenment, Silk is shown things that he could not possibly have seen or known otherwise: he is shown the stars, something completely foreign to those living on the inner surface of the hollowed-out asteroid that is the "starcrosser Whorl"; he is shown the inner workings of the "clockwork" ship and given a mission to save it (or rather, its inhabitants); and he is shown scenes from the life of Christ. A supernatural enlightenment would seem to be the only possible explanation for Silk coming to possess this knowledge. Theories that Silk received this "enlightenment" from a Sacred Window or "glass" (downloading the information into his mind) are also flawed, since there was no such object on the ball court where he received his enlightenment (furthermore, this interpretation has been argued against by Wolfe in the Q&A linked to above).
Doctor Crane's explanation also seems to be medically dubious, since he attributes Silk’s "cerebral accident" to a burst blood vessel in the Wernicke's area of the brain, located in the temporal lobe. Trauma to this area usually results in aphasia, "the partial or complete loss of language abilities," resulting in outbursts of unintelligible speech and a total loss of language comprehension (Bear, Connors, and Paradiso 640, 645-47). Silk experiences none of these symptoms, and is seen fluently talking to Maytera Marble and the students of the palaestra immediately following the incident. Although the Wernicke's area is working in overdrive during temporal lobe hallucinations, and can be connected to the hearing of incomprehensible voices, it is not connected to visual hallucinations, such as the visions that Silk receives (Shergill). Furthermore, Silk understands what the many voices (which he believes are all the one voice, somehow) are saying to him. Hence, Crane's hypothesis would seem to fail on a medical level, as well as a narrative one.
In spite of its apparent inability to explain his enlightenment, Crane's scientific explanation still troubles Silk, and causes him to doubt the Outsider and his own experiences:
But the Outsider had doubtless been, as Doctor Crane had maintained, no more than a vein’s bursting.
Or had Doctor Crane—who had thought himself, or at any rate called himself, and agent of the Rani—been in truth an agent of the Outsider? Doctor Crane had made it possible for him to proceed in his attempt to save the manteion despite his broken ankle; and Doctor Crane had freed him when he had been taken by the Ayuntamiento. It was conceivable, even likely, that Doctor Crane's skepticism had been a test of faith.
Had he passed?
… If he had, he would almost certainly be tested again, after this surrender to doubt. (Caldé 273)
Silk overcomes his doubts and begins to see Crane's scepticism as a test of faith; a test that would seem to apply to the reader as much as it does to Silk. Nick Gevers argues that scientific rhetoric like Doctor Crane's "entices the secular-minded reader into Wolfe’s text. Then, too late, the reader realises that scientific analysis will not serve, that a religious paradigm must take over" ("Five Steps towards Briah"). The reader, then, is forced into accepting, at least within the universe of Wolfe's Sun books, the actuality of a god that Silk calls the Outsider, which is, undoubtedly, a form of Wolfe’s own Catholic God. It is for this reason that Gevers rightly calls The Book of the Long Sun "a masterpiece of subversive persuasion" ("Five Steps").
Page numbers refer to omnibus editions of Nightside of the Long Sun and Lake of the Long Sun collected in Litany of the Long Sun (New York: Orb-Tom Doherty Associates, 2000); and Caldé of the Long Sun and Exodus from the Long Sun collected in Epiphany of the Long Sun (New York: Orb-Tom Doherty Associates, 2000).