In Nabokov's "Verses and Versions" there is a French poem "translated by Sybil Shade". Its original, "Odelette," was written by Henri de Régnier ( 1804-1936) and the title Nabokov/Sybil chose for the English is "Passing of Youth".

 

To the poem, in a PS, was added a note, dated December 25, 1962: "a prettier paraphrase of the first stanza, to cure the tautological last line, would be: " What sweetness in my every thought[...] those rocking barks with nought/ In their extinguished lamp but night."

 

In the editor's notes we find: "French text: Nabokov encountered this poem in a translation competition in the Sunday Times December 23, 1962. From Henri de Régnier, Vestigia Flammae. Poèmes (Paris: Mercure de France, 1921),114."

 

QUERY: I would like to learn if anyone knows if Nabokov chose the name "Sybil Shade" as a pseudonym, or what were his motivations.

I found in it an added irony for "our" Sybil was presented as translating English poets into French.

Here the process is inverted: she works over from the French into English.