So far as I know Wagner only on one occasion addressed the question why Siegfried had to die. According to a visitor to Wagner’s home Tribschen in 1869, Valentina Serova, Wagner said Siegfried had to die because evil, exemplified by Alberich, always wins in the real, objective world:
“[Speaking of someone present at Wagner’s home Tribschen on 7/8/69, who was asking Wagner to explain seeming contradictions in the Ring’s plot, Serova recorded his following question, and Wagner’s answer to it:] … why must Siegfried be killed?’ the questioner went on.
[Wagner answered:] ‘Because evil always prevails over good. Alberich’s powers are invincible: he is the spirit of evil who pursues his dark ends with a grim, unflinching determination. And he passes on this resolve to his son Hagen.” [752W-{7/8/69} Valentina Serova’s reminiscence of a visit to Tribschen on 7/8/69: WR, p. 203]
[T.3.2: G]
The mourners, including Gunther, now pick the dead Siegfried up and carry him in moonlight back to Gibichung Hall, to the accompaniment of one of the most famous orchestral passages from the Ring, ‘Siegfried’s Funeral Procession (March),’ which is often performed as an independent piece in the concert hall, a staple of the Western classical repertoire:
(Orchestral Interlude: Siegfried sinks back and dies. Motionless grief on the part of those around him. #87’s drum accompaniment “Crisis”; #177ab; #66; #87 drum accompaniment “Crisis”; #177ab; #66 [but evidently with an end frag which was heard in association with #66, #81, and #87 in S.3.2, when Wotan told Siegfried that if Siegfried knew who Wotan was, he’d respect him, and that Siegfried’s disrespect is painful to Wotan. Is this the #81 or #164 grace-note twist?] Night has fallen. At Gunther’s silent command, the vassals lift up Siegfried’s body and, during the following, carry it away slowly in solemn procession over the cliff top. [#: three long, ever louder, higher notes in the bass]; #177a on brass; #177b; #71; #177ab: #70; #63/#66. The moon breaks through the clouds and casts an increasingly bright light on the funeral procession which has now reached the top of the cliff. #40; #64; #177ab: [rising] Mists have risen from the Rhine and gradually fill the whole of the stage, on which the funeral procession has already become invisible, so that it remains completely hidden throughout the musical interlude. #66/#177 frag; #57; #177a in major [and loud]; #92/#177b major; #92c, #71 vari “Hero,” or #57 vari [i.e., #92’s cadential figure or end frag, heard in association with Bruennhilde’s following action from V.3.1: “(She takes the fragments of Siegmund’s sword from beneath her coat of mail and hands them to Sieglinde),” and heard also when Bruennhilde says: “… receive his name from me,” as she names Sieglinde’s as yet unborn child Siegfried]; #148; #177a? [loud]; #148; #177b; #148. From this point onwards the mists begin
