[He'd been staring at that stone, only partly listening to her. That last comment make him turned, however, expression hard]

It's not like I forgot to turn the lights off or burned someone's cake here, Sheena. [He gestures to the mess around them] I've destroyed everything, made it so people have to pay for the luxury of breathing air that won't make them cough so much they could hack up a lung. Nothing can grow here, very little can live here. It's a wasteland.

[He glances beyond her, off to that point in the distance where he knows Thneedville lies] So no, I can't forgive myself for this mistake.