Jeff Jacoby has been an op-ed columnist for The Boston Globe since February 1994.

Holocaust Remembrance Day always falls during the week that follows Passover. At first glance, the two would seem to have little in common — one memorializes the millions of European Jews annihilated by Nazi Germany; the other commemorates the deliverance of the Jews from slavery in ancient Egypt.

Yet for all their obvious differences, a fundamental similarity links these two crucial chapters in Jewish history. Both were attempts at genocide — and in both cases the perpetrators justified their savageries by claiming that they were the real victims, threatened by the people they intended to wipe out.

At the Passover Seder, retelling the 3,000-year-old story, Jews read the passage from Exodus in which Pharaoh rationalizes the lethal repression he is about to inflict on the Hebrews. "Come, let us deal wisely with them," he declares. "Otherwise they may become so many that if there is a war they will join our enemies, fight against us, and leave the land." His notion of dealing wisely: slave labor, followed by mass murder. "Then Pharaoh commanded all his people, ‘Every boy that is born to the Hebrews, you shall throw into the Nile.’ "

Thirty centuries later, the same pattern preceded the Holocaust...