At the end of the novel, Wolf’s body shutting down from a mysterious illness is an example of situational irony. The situation is ironic because he has spent his entire life overpowering others with his tremendous physical strength; however, as his illness progresses, he loses the physical strength he has always relied on. Maud and Humphrey care for him rather than killing him, even though (as Wolf openly admits), he would kill them immediately if their roles were reversed. This adds another layer of irony to the situation, because Humphrey was previously at the mercy of Wolf, who imprisoned him on the Ghost by threatening to kill him.
Even when Wolf’s physical body has ceased to function, his self—or as Maud and Humphrey might say, his spirit—lives on, as evidenced by the notes he writes to them. In Chapter 37, after Wolf has lost the use of his voice and can only communicate in notes, he writes:
“And yet I am all here, Hump […] I can think more clearly than ever in my life before. Nothing to disturb me. Concentration is perfect. I am all here and more than here.”
It was like a message from the night of the grave; for this man’s body had become his mausoleum. And there, in so strange a sepulchre, his spirit fluttered and lived. It would flutter and live till the last line of communication was broken, and after that who was to say how much longer it might continue to flutter and live?