After a lot of "desultory clicking" # to find out more about V.Nabokov's
frequent references to the arctic regions and to polar expeditions (Humbert
Humbert's in "Lolita", for example, Krolik in "Ada", Kinbote's associations
to "parhelia"), I came to various old sightings from which I selected two
(or three).

The first one is "Nabokov's Secret Knowledge" [
https://petersonion.wordpress.com/2010/07/05/nabokovs-secret-knowledge/] and
here are a few excerpts:

"Consider the following statement by Vladimir Nabokov: "To be quite candid -
and what I am going to say now is something I have never said before, and I
hope that it provokes a salutary chill - I know more than I can express in
words, and the little that I can express would not have been expressed, had
I not known more (Strong Opinions, pg. 45)." He made this statement in the
Playboy interview in response to Toffler's asking him whether or not he
believed in God. For some time now these words have not failed to provoke
their intended "chill" when I think about them. Whether it is "salutary" or
not remains debatable, since it has thrown again into confusion for me an
area of inquiry I have long (and very happily) considered settled. I mean
the question of spiritual enlightenment [snip] ...why do those innocuous
words, quoted above, bother me coming out of Nabokov's mouth?
They bother me simply because they have opened up the question again.   I
could find reasons to suspect every historical mouth-piece of enlightenment
(Buddha, Jesus, Plato, the Zohar, etc.) for merely seeking to furnish
authority for some agenda, whether political, moral or instinctual. So I
had reason also to doubt the reality of enlightenment. But to me, Vladimir
Nabokov is not mere dictum. I can think of no reason to suspect what he has
to say outside the scope of his novels. His hunger for being, as he put it,
"fantastically deceitful," was satisfied with them. So if what he is
suggesting in that statement in Playboy is that he is enlightened... then
I'm not sure, I sort of have to rethink the issue again.
This begs the following questions: (1) Why is Nabokov such a credible
source, and (2) How can we know Nabokov is speaking about enlightenment?
Nabokov is a credible source because he is perhaps the only writer in
history short of maybe Shakespeare who had no discernable agenda. Beyond
being a master of style, he is notable for being the opposite of an
ideologue.[   ] His family was dispossessed and his father was murdered by
ideologues: he was intimate with the consequences of hypocrisy.
Moreover his books are visionary, not idealistic. In literary metaphor as
well as lepidopteral taxonomy, his goal was precision. The best way of
triggering, as he saw it, the aesthetic experience, was to assist clarity in
understanding. Nothing primitive, obscuritanist or mystical. For Nabokov
consciousness - specifically human consciousness - was an unqualified good
and warranted expansion, not through mystical mortification of the self, but
through the orderly identification of reality.
How I know he is talking about enlightenment is slightly harder to prove. I
think this because, first of all, the statement's context was on a question
of God, not art or science; and secondly, because using the phrase "I mean
more than I can say in words" concerning emotions and so forth is a cliché
of the worst sort, and that was not Nabokov's way. He clearly meant to
emphasize some sort of significant difference between himself and others; a
possession more than just talent that made his books possible. He says
"know" - so what kind of secret knowledge does he have, and won through what
kind of elusive experience?
Below is a passage from his abandoned novel Ultima Thule. The premise is
that Truth was one evening revealed to a man named Falter, and it was fatal.
He cried out all night in mortal pain - but somehow he survived the
onslaught. When his neighbors sent the doctor the next morning to check on
him, Falter spoke a certain word to him and it killed him. I can think of
only two other sources with this concept of "fatal enlightenment": UG
Krishnamurti and the ancient Hebrews. But Krishnamurti was after Nabokov's
time, and the Bible gives no glimpse into the experience. [   ] "For the
sake of somehow starting our talk, I shall temporarily accept your refusal.
Let us proceed ab ovo. Now then, Falter, I understand that the essence of
things has been revealed to you." [   ] For whatever reason, this and the
rest of passage makes more sense to me than any sutra or Upanishad I have
had the misery to slog through. I feel that the words could only have been
written from within the thing they are speaking about. The problem, of
course, is that this passage is in a work of fiction, and therefore falls
within the scope of Nabokov's being "fantastically deceitful."

The other one is more recent: Ice Friday: Vladimir Nabokov's Essential Truth
Posted on July 1, 2016
<http://mcphedranbadside.com/ice-friday-vladimir-nabokovs-essential-truth/>
http://mcphedranbadside.com/ice-friday-vladimir-nabokovs-essential-truth/

"Wait! There, I feel once again that I shall really express myself, shall
bring the words to bay.
<http://mcphedranbadside.com/ice-friday-vladimir-nabokovs-essential-truth/im
g_4549/>
I myself picture all of this so clearly, but you are not I, and therein lies
the calamity."
(From Vladimir Nabokov's Invitation to a Beheading)

From all the definitions and characterizations of Ultima Thule (even
considering the very real Arctic post founded by Kund Rasmussen) I selected
one by Virgil that I found through wikipedia:" Virgil
<https://en.wikipedia.org/wiki/Virgil> coined the term Ultima Thule
(Georgics <https://en.wikipedia.org/wiki/Georgics> , 1. 30) meaning furthest
land as a symbolic reference to denote a far-off land or an unattainable
goal."[12] <https://en.wikipedia.org/wiki/Thule>

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* -.borrowing Justin E A Smith's words ( http://www.jehsmith.com/1/ )
In one of his titles in his blog, from 2013, he mentions V. Nabokov: "I
consider myself politically progressive, but there are a few major sticking
points that keep me perpetually at odds with my would-be allies. I hold in
utter contempt anyone who would attempt to dictate to me a list of things I
am forbidden to say, and it is generally more from the left than from other
quarters that such dictation comes. I am part of that minority that
continues to consider political correctness a real threat, and not a
momentary excess of the early 1990s, when we heard all that reactionary
huffing about how soon enough they'll be making us say 'vertically
challenged' instead of 'short' and so on. I speak not with Rush Limbaugh but
with Vladimir Nabokov when I say that I am horrified by the limitation of
free expression, by which I don't mean the usual 'expression of unpopular
ideas' beloved of 'card-carrying members of the ACLU', but rather the
creative use of language where a Schillerian free play of the imagination is
the only source of regulation. I believe the desire to regulate externally
stems not just from a misunderstanding of how political progress is made,
but also of how language functions." JULY 6, 2013
http://www.jehsmith.com/1/2013/07/punish-the-jester.html