I noticed V.Nabokov's peculiar wording (in translation) of the first paragraph of "Christmas":  "AFTER walking back from the village to his manor across the dimming snows, Sleptsov sat down in a corner, on a plush-covered chair which he never remembered using before. It was the kind of thing that happens after some great calamity." It is impossible to realize that you’ve "never remembered before" a particular thing or moment. You either remember it or you don't. The "never" in the sentence quoted above has been placed in a peculiar position  and it’s followed by: "it was the kind of thing that happens after some great calamity," indicating the occurrence of some kind of uncomfortable thought or emotion.

In "A Disturbance of Memory on the Acropolis," written as a birthday-letter addressed to Romain Rolland, Freud describes the strange feeling he experienced when he first visited the Acropolis in Athens. He was so filled with wonderment to have made it there, at last, that a thought crossed his mind: "So the Acropolis does, in fact, exist," as if he’d never pored over the maps of Athens and explored its historical sites without having to question their reality. He named his disturbance as a "derealization."*

It is my impression that V.Nabokov himself wasn’t unfamiliar with the “Unheimlich”, with “derealizations” or “depersonalizations” and this is why I wonder if, in “Christmas” ( we find other instances in “The Eye”, “Despair” and perhaps even in “Lolita”), he wasn’t indicating a similar disturbing “calamity” associated to death of a loved relative and a return to his birthplace.

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* - quoting Freud "so I will conclude by saying briefly that the whole psychical situation, which seems so confused and is so difficult to describe, can be satisfactorily cleared up by assuming that at the time I had (or might have had) a momentary feeling: ‘What I see here is not real.’ Such a feeling is known as a ‘feeling of derealization’. I made an attempt to ward that feeling off, and I succeeded, at the cost of making a false pronouncement about the past. These derealizations are remarkable phenomena which are still little understood. They are spoken of as ‘sensations’, but they are obviously complicated processes, attached to particular mental contents and bound up with decisions made about those contents. They arise very frequently in certain mental diseases, but they are not unknown among normal people, just as hallucinations occasionally occur in the healthy. Nevertheless they are certainly failures in functioning and, like dreams, which, in spite of their regular occurrence in healthy people, serve us as models of psychological disorder, they are abnormal structures. These phenomena are to be observed in two forms: the subject feels either that a piece of reality or that a piece of his own self is strange to him. In the latter case we speak of ‘depersonalizations’; derealizations and depersonalizations are intimately connected. There is another set of phenomena which may b eregarded as their positive counterparts - what are known as ‘ fausse reconnaissance ’, ‘déià vu’,‘déjà raconté’ etc., illusions in which we seek to accept something as belonging to our ego, just as in the derealizations we are anxious to keep something out of us. A naïvely mystical and unpsychological attempt at explaining the phenomena of ‘ déjà vu ’ endeavours to find evidence in it of a former existence of our mental self. Depersonalization leads us on to the extraordinary condition of ‘ double conscience ’, which is more correctly described as ‘split personality’. But all of this is so obscure and has been so little mastered scientifically that I must refrain from talking about it any more to you. It will be enough for my purposes if I return to two general characteristics of the phenomena of derealization. The first is that they all serve the purpose of defence; they aim at keeping something away from the ego, at disavowing it. Now, new elements, which may give occasion for defensive measures, approach the ego from two directions - from the real external world and from the internal world of thoughts and impulses that emerge in the ego. It is possible that this alternative coincides with the choice between derealizations proper and depersonalizations. There are an extraordinarily large number of methods (or mechanisms, as we say) used by our ego in the discharge of its defensive functions.” (S.Freud) http://pt.scribd.com/doc/68155992/A-Disturbance-of-Memory-on-the-Acropolis