Now, Bob, who'd been observing Jack carefully for many years, had observed that when these moments arrived, Jack was almost invariably possessed by something that Bob had heard about in Church called the Imp of the Perverse. Bob was convinced that the Imp of the Perverse rode invisibly on Jack's shoulder whispering bad ideas into his ear, and that the only counterbalance was Bob himself, standing alongside, counseling good sense, prudence, caution, and other Puritan virtues. *