Pnin, Nabokov's 13th novel, and 4th in English, Doubleday, 1957, reprinted, R. Bentley, 1982. (Pnin can be found in many public libraries and is available online from Amazon.com and from Barnes & Noble. Also published as a Penguin Classic by Penguin UK.)

"A score of small butterflies, all of one kind, were settled on a damp patch of sand, their wings erect and closed, showing their pale undersides with dark dots and tiny orange-rimmed peacock spots along the hindwing margins; one of Pnin's shed rubbers disturbed some of them and, revealing the celestial hue of their upper surface, they fluttered around like blue snowflakes before settling again.
'Pity Vladimir Vladimirovich is not here,' remarked Chateau. 'He would have told us all about these enchanting insects.'"

Pnin is a charming and deeply-felt novel, and has been considered Nabokov's most appealing book. Essentially a series of fondly-observed anecdotes, by turns touching and amusing, Nabokov called upon his faculty experiences to recount the tale of eccentric, decent, somewhat bewildered Russian émigré Professor Timofey Pnin. Pnin's misadventures are comical, yet he somehow survives with his dignity intact, and thus his story resonates with universal appeal. Pnin may serve as the best introduction to Nabokov's works for the uninitiated.

Pnin is the only novel for which Nabokov included the disclaimer, "All characters in this book are fictitious, and any resemblance to actual persons, living or dead, is purely coincidental."