Young Jim, his father, and the mattress (pp. 502–503)
Because of the lack of resistance or friction against the bare floor, the knob rolled this way for a long time as I watched over the edge of the comforter and mattress, holding my glasses in place, completely distracted from the minor-D shriek of the vacuum below. It occurred to me that the movement of the amputated knob perfectly schematized what it would look like for someone to try to turn somersaults with one hand nailed to the floor. This was how I first became interested in the possibilities of annulation.
Context
The scene's last words, and the book's origin-myth for its central concept, in JOI's own voice. The image he lands on — somersaults with one hand nailed to the floor — is perfect circular motion and mutilated entrapment in a single figure, which is the theme in one sentence. (The same image resurfaces decades later as E.T.A. folklore: see the annulation lecture, p. 570.) (The scene's last line is confirmed on print p. 503, which begins "comforter and mattress" and ends "the sudden sauna-".)