Chapter 4, Part Two, of Ada is Van's lecture on dreams. According to Van, "there are the professional dreams and there are the erotic ones:"

In the professional dreams that especially obsessed me when I worked on my earliest fiction, and pleaded abjectly with a very frail muse ('kneeling and wringing my hands' like the dusty-trousered Marmlad before his Marmlady in Dickens), I might see for example that I was correcting galley proofs but that somehow (the great 'somehow' of dreams!) the book had already come out, had come out literally, being proffered to me by a human hand from the wastepaper basket in its perfect, and dreadfully imperfect, stage - with a typo on every page, such as the snide 'bitterly' instead of 'butterfly' and the meaningless 'nuclear' instead of 'unclear.' Or I would be hurrying to a reading I had to give - would feel exasperated by the sight of the traffic and people blocking my way, and then realize with sudden relief that all I had to do was to strike out the phrase 'crowded street' in my manuscript.

Van's first novel is Letters from Terra. (2.2) In his "Letters of a Russian Traveller" Karamzin tells about the remarkable dream he had in Lausanne after returning from Vevey:

От сильного волнения в крови провёл я ночь беспокойно и видел сны, из которых один показался мне достойным замечания. Мне привиделось, что я в большой зале стою на кафедре и при множестве слушателей говорю речь о темпераментах. Проснувшись, схватил я перо и написал, что осталось у меня в памяти, из чего, к моему удивлению, вышло нечто порядочное. Судите сами - вот сей отрывок:
"Темперамент есть основание нравственного существа нашего, а характер - случайная форма его. Мы родимся с темпераментом, но без характера, который образуется мало-помалу от внешних впечатлений. Характер зависит, конечно, от темперамента, но только отчасти, завися, впрочем, от рода действующих на нас предметов. Особливая способность принимать впечатления есть темперамент; форма, которую дают сии впечатления нравственному существу, есть характер. Один предмет производит разные действия в людях - отчего? От разности темпераментов или от разного свойства нравственной массы, которая есть младенец".
Вы мне поверите, что я не прибавил и не убавил, а написал слова точно так, как сновидение впечатлело их в моей памяти. Кто изъяснит связь идей, во сне нам представляющихся? И каким образом они возбуждаются? Я совсем не думал наяву о темпераментах и характерах: отчего же мечтал об них?

(Karamzin dreamt of giving a lecture on temperaments. Upon waking up Karamzin wrote down word for word what he recalled of the lecture he gave in his dream.)

"The dusty-trousered Marmlad and his Marmlady" mentioned by Van hint, of course, at Marmeladov and his wife, the characters in Dostoevski's "Crime and Punishment." The characters of Dostoevski's Besy ("The Possessed") include the novelist Karmazinov (a caricature on Turgenev). Btw., in Paris Turgenev attended a lecture on pornography with illustrative scenes involving live people.

From Ada's letter to Van: For her [Dasha Vinelander] you're le beau ténébreux, because once upon a time, once upon libellula wings, not long before my marriage, she attended - I mean at that time, I'm stuck in my 'turnstyle' - one of your public lectures on dreams, after which she went up to you with her latest little nightmare all typed out and neatly clipped together, and you scowled darkly and refused to take it. (3.7)

In Turgenev's play "A Month in the Country" (1850) Natalia Petrovna calls Rakitin "beau ténébreux."

Dorothy preambled her long-delayed report on her pet nightmare with a humble complaint ('Of course, I know that for your patients to have bad dreams is a zhidovskaya prerogativa'), but her reluctant analyst's attention every time it returned to her from his plate fixed itself so insistently on the Greek cross of almost ecclesiastical size shining on her otherwise unremarkable chest that she thought fit to interrupt her narrative (which had to do with the eruption of a dream volcano)... (3.8)

Dorothy Vinelander eventually marries a Mr Brod or Bred, tender and passionate, dark and handsome, who traveled in eucharistials and other sacramental objects throughout the Severnïya Territorii and who subsequently was to direct, and still may be directing half a century later, archeological reconstructions at Goreloe (the 'Lyaskan Herculanum'); what treasures he dug up in matrimony is another question. (ibid.)

In his poem K dobrodeteli ("To Virtue", 1802) Karamzin says:

Злодей на Этне строит дом.

(An evil person builds his house on Etna.)

According to Karamzin,

Бесчувственность есть ад того,
Кто зло творит без сожаленья.

(Insensitivity is the hell of the one

who does evil without regret. Ibid.)

Karamzin is the author of the twelve-volume "History of Russian State" (from ancient times to 1612) and short stories Bednaya Liza ("Poor Liza", 1792), Sierra-Morena (1793) and Ostrov Borngol'm ("The Island of Bornholm", 1794). The latter story is about incest.

In a letter of August 17, 1825, to Zhukovski Pushkin (who worked on Boris Godunov in Mikhaylovskoe) says that he is delighted with the last two volumes of Karamzin's History: Что за чудо эти 2 последние тома Карамзина! какая жизнь! c’est palpitant comme la gazette d’hier, писал я Раевскому. In the same letter Pushkin mentions Rome and Mount Vesuvius: Вижу по газетам, что Перовский у Вас. Счастливец! он видел и Рим и Везувий.*

A fragment from Van's Texture of Time (Part Four of Ada) seems also relevant:

At the third and last lecture, on the Future ('Sham Time'), after working perfectly for a few minutes, my secretly recorded voice underwent an obscure mechanical disaster, and I preferred simulating a heart attack and being carried out into the night forever (insofar as lecturing was concerned) to trying to decipher and sort out the batch of crumpled notes in pale pencil which poor speakers are obsessed with in familiar dreams (attributed by Dr Froid of Signy-Mondieu-Mondieu to the dreamer's having read in infancy his adulterous parents' love letters).

*in a letter (published by Zhukovski in Northern Flowers) of June 3, 1824, from Sorrento V. A. Perovski describes Vesuvius, Herculanum and Pompeii