It occurs to me,that if you read Pale Fire the way I do,
that Shade becomes significantly unglued at the end;
if so then you can see a fundamental similarity between it
& Poe's The Raven: both attempt to chronicle
the decline of the mind into some form of dementia.
I think Poe's poem pales compared to Pale Fire.
The descent to be believed must extend long enough
to depict some amount of progression.
Poe is constricted from making the poem longer
by the use of large repetitive structures.
These are used to denote the coming madness, perhaps,
and constitutes the thing that many people enjoy about the poem,
its large grain repetition that connotes regression
and imparts a kind of charming, magical quality
to the coming decline.
But, again, these large grain patterns argue against
writing a longer poem.
The device becomes boring.
Nabokov, on the other hand,
uses a thousand-and-less-one lines in his attempt.
And he succeeds,
brilliantly I think.
~gsl