The Cradle Rocks above an Abyss

The mind-blowing opening paragraph of Nabokov's Speak, Memory :

The cradle rocks above an abyss, and common sense tells us that our existence is but a brief crack of light between two eternities of darkness. Although the two are identical twins, man, as a rule, views the prenatal abyss with more calm than the one he is heading for (at some forty-five hundred heart-beats an hour). I know, however, of a young chronophobiac who experienced something like panic when looking for the first-time at home-made movies that had been taken a few weeks before his birth. He saw a world that was practically unchanged—the same house, the same people—and then realized that he did not exist there at all and nobody mourned his absence. He caught a glimpse of his mother waving from an upstairs window, and that unfamiliar gesture disturbed him, as if it were some mysterious farewell. But what particularly frightened him was the sight of a brand-new baby-carriage standing there on the porch, with the smug, encroaching air of a coffin; even that was empty, as if in the reverse course of events, his very bones had disintegrated.