In Canto Three of his poem John Shade (the poet in VN’s novel Pale Fire, 1962) describes his visit to Mrs. Z. (who saw a tall white mountain during her heart attack) and, at the end of the Canto, mentions some faint hope:
Stormcoated, I strode in: Sybil, it is
My firm conviction - "Darling, shut the door.
Had a nice trip?" Splendid - but what is more
I have returned convinced that I can grope