" But there’s no wall down there, Keller thinks, smiling. And there never will be. A border is something that divides us but also unites us; there can be no real wall, just as there is no wall that divides the human soul between its best impulses and its worst. Keller knows. He’s been on both sides of the border. He takes Mari’s hand and together they limp back down the hill. "

― Don Winslow , The Border (Power of the Dog, #3)