After I got a VN posting with SERGEI KARPUKHIN´s "mea culpa" in answer to Dmitri´s message, quite desultorily  I tried to read a little more about the article on VN and Mlle O that came at the end of his mailing. What is written there as VN´s is not exactly what VN wrote in SM (Vintage, page 110)
In a rough translation from the French -  corrections are welcome: " The writer, in search for truth, tries to recover the world as he perceived it when still a child.  With a tenderness that resembles Proust´s own for his characters, Nabokov built the unforgettable portrait of the one that was for him much more than a simple governess: " I imagine paradise as an endless book which she continuously read by the light of an eternal candle" 
The original:
L'écrivain, en quête de vérité, tente de ressaisir le monde qu'enfant, il
percevait. Avec une tendresse proche de celle de Proust pour ses
personnages, Nabokov dresse le portrait inoubliable de celle qui fut bien
plus qu'une simple institutrice : «Je m'imagine le paradis comme un livre
interminable qu'elle lirait sans se lasser à la lumière d'une bougie
éternelle.»
 http://www.liberation.fr/page.php?Article=281604
 Roman. Vladimir Nabokov /Mademoiselle O
Par Hélène PERRAUDEAU
vendredi 11 mars 2005
VN wrote: " I am in acute distress, desperately trying to coax sleep, opening my eyes every few seconds to check the faded gleam, and imagining paradise as a place where a sleepless neighbor reads an endless book by the light of an eternal candle" .
Here we find the slivers of light and tinkling bottles that constantly emerge in Ada and elsewhere: " those inexorable steps, plodding along the passage and causing some fragile glass object, which had been secretly sharing my vigil, to vibrate in dismay on its shelf"...  And here we find a small boy in pajamas, plagued by regular night terrors while he hopes that Mademoiselle could linger a littile longer before putting out the lights. There is not special tenderness for her, Mlle O, in this particular example. In French, her warm companionship is suggested and paradise and eternity a place linked to her!  .