Why is it great? Nabokov is masterful here, not just stylistically but emotionally. He interrupts Humbert Humbert's grotesque pursuit of Lolita by having him address the reader directly with an abject plea for understanding, a jarring moment that makes us queasy and disgusted but also arouses a shiver of pity. In that one sentence, we've been co-opted. And it captures the character of Humbert Humbert perfectly: in denial, but always, always, hearing the distant bell of culpability.