Nabokov's "Pale Fire" & the Mourning Cloak Butterfly

Finished Emma (singing the De profundis I buried her yesterday); have a few more pages left on Emants' A Posthumous Confession; started a Kindle version (hope the commentary has hyperlinks back to the poem) of Nabokov's Pale Fire (read it last maybe 7 or more years ago).

Re Pale Fire's Preface (ghost written by Charles Kinbote), I'll only copy out the wonderful sentence evoking the mourning cloak butterfly (where I live there's a few stands of cottonwoods that lure them in: I wait every year for the little mummies to evict the ashen tenants fringed with yellow):

As a rule, Shade destroyed drafts the moment he ceased to need them: well do I recall seeing him from my porch, on a brilliant morning, burning a whole stack of them in the pale fire of the incinerator before which he stood with bent head like an official mourner among the wind-borne black butterflies of that backyard auto-da-fe.