The first time I visited Rwanda, I went looking for monsters, albeit a different category of monster—the kind that isn't relegated to B movies. I had heard about the 1994 genocide that had left one million people dead—tortured, raped, viciously murdered—and somehow I thought it would be easy to spot the perpetrators. I naïvely assumed I would be able to look men and women in the eyes and tell if they had ben involved. I was full of self-righteous judgment.

What I found left me puzzled, confused, and ultimately frightened. Instead of finding leering, menacing creatures, I met men and women who looked and behaved a lot like me. They took care of their families, went to work, chatted with their neighbors, laughed, cried, prayed, and worshiped. Where were the monsters? Where were the evildoers capable of heinous acts? Slowly, with a deepening sense of dread, I understood the truth: There were no monsters in Rwanda, just people like you and me. …

Before that trip, I can't tell you the number of times I reacted to evil I read about or witnessed by saying, "I would never do that!" But thousands of years of bloody human history prove differently. Fifty-four years of my own history prove differently. We are all proficient in our ability to conceive, plan, and execute evil. Of course, we don't call it evil when we're the ones involved. But it is. As French writer La Rochefoucauld observed, "There is hardly a man clever enough to recognize the full extent of the evil he does." You might as well face the shameful truth: You and I, put in the right situation, will do absolutely anything. Given the right circumstances, I am capable of any sin. I've grown more afraid of the monster lurking in the dark corners of my soul than of any monster lurking in the dark corners of my house.