“Now it is perfectly true that nothing unifies a group more effectively than a threat, particularly an enemy. This may be external, but an internal enemy, a traitor, a trouble-maker, a deviant, will do as well, and the group feels better if it has someone to bully and despise. But while every group and society contains despised groups and individuals, they are not normally killed or even necessarily ill-treated, let alone selected for slaughter. Not surprisingly, it is very hard to find eyewitness accounts of human sacrifice, but the following example is nevertheless very instructive.”