Actualy "Erlkönig" may be translated as "Alder King" but, in B.Boyd's "The Magic of Artistic Discovery", I only found, on page 161, an indirect reference to this translation, when B.Boyd mentions how King Charles II rushes from Odon's car and repeats to himself the "haunting lines" of Goethe's poem "about the erlking, hoary enchanter of the elf-haunted alderwood".

There are several mentions to alder and alderwood in Pale Fire. In Kinbote's commentary to line 894 ( with the heading "A King" ) we find a German visitor " who by some quirk of alderwood ancestry had been alone to catch the eerie note that had throbbed and was gone".

Word plays in Pale Fire (Canto Three):

Soon afterwards, Shade's verses continue:

You and I,
And she, then a mere tot, moved from New Wye
To Yewshade, in another, higher state"

Now we get to Kinbote comments on note to line 501: "L' if The yew in French. It is curious that the Zemblan word for the weeping willow is also 'if" ( the yew is tas )" .

Also in the Index there is an entry under Kinbote, Charles, Dr.: "his surprise at realizing that the French name of one melancholy tree is the same as the Zemblan for another."

We find there is another play with the rhymes for Shade's "I" with "Wye", the latter an anagram of "Yew" ( "You, Shade" ) and his metamorphosis into "another, higher state". Also a suggestion that the "You" is the same as the Zemblan for "another"?

I also found a link between the discussion about "yewtrees" and "willows" ( by Kinbote) and the Alder - but it is a complicated line of associations that start with the Alder in Celtic folklore ( linked to the god Bran whose totem animal is the Raven), passing through Poe's poem "The Raven" rasping against the window pane and initially taken for the wind ( just like in Shade's poem, as annotated by Kingbote in conection to Goethe's Erlkönig, T.S.Eliot's and Webster's poems). Then, we return to Goethe's Erlkönig ( "Alder King") where a child is being abducted by him and his daughters, while his father interprets the boy's hallucinations as being "gray willows" ...
Gray willows, or "If" ( in Zemblan) and the same as the English "yew/you" .
In the Ogham alphabet, the Druids allocated the letter “F” the third consonant to the Alder( "L' if" ?)

Once upon a midnight dreary, while I pondered, weak and weary,
Over many a quaint and curious volume of forgotten lore,
................
Soon again I heard a tapping, something louder than before,
"Surely," said I, "surely, that is something at my window lattice.
Let me see, then, what thereat is, and this mystery explore.
Let my heart be still a moment, and this mystery explore.
" 'Tis the wind, and nothing more."

Here the penultimate verses of Goethe's Erlkönig:

Mein Vater, mein Vater, und siehst du nicht dort
Erlkönigs Töchter am düstern Ort? -
Mein Sohn, mein Sohn, ich seh es genau:
Es scheinen die alten Weiden so grau. -

»Ich liebe dich, mich reizt deine schöne Gestalt;
Und bist du nicht willig, so brauch ich Gewalt.«
Mein Vater, mein Vater, jetzt faßt er mich an!
Erlkönig hat mir ein Leids getan! -

In Pale Fire we find a foreboding in lines 479/480 ( "was that the phone?" ...window-rubbing") and then we reach Canto Three, lines 653/660 ( We heard the wind...Twigs at the windowpane...Phone ringing"), followed by the clear Erlking reference on lines 662/664 - the latter annotated by Kinbote.

Here is the extract from The Waste Land ,T.S. Eliot (1888-1965).

'What is that noise?'
The wind under the door.
'What is that noise now? What is the wind doing?'
Nothing again nothing.
'Do
'You know nothing? Do you see nothing? Do you remember
'Nothing?'

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