At the beginning of his poem John Shade (the poet in VN’s novel Pale Fire, 1962) says that he was the shadow of the waxwing slain by the false azure in the windowpane:
I was the shadow of the waxwing slain
By the false azure in the windowpane;
I was the smudge of ashen fluff - and I
Lived on, flew on, in the reflected sky. (ll. 1-4)