Can anyone doubt that rather than duplicate the parturitional feat whereby a mountain spews forth a mouse, Nabokov opts for the reverse maternal drama in which a mouse risks conception to bring forth a mountain? Ostensibly in Ada, the authorial quest involves the pursuit of Time by Memory, the two being courtly lovers of the mind whose Proustian infidelities often leave us wondering whether in our romance with the past we haven't somehow confused the fictional swain with the autobiographical cuckold. But the real obsession of the book (and of all Nabokov's works since his first "American" novel, Lolita) is with facts, and having grasped this, we should have no difficulty making sense of a style whose passion for instructing the reader (mostly in things he never dreamt he was ignorant of) is discernible on every page.

Instruction, of course, suggests the deploying of facts, and the discreet...