Think what Passover meant for centuries: the blood libel, the repellent and groundless charge that Jews stole Christian children, crucifying and killing them, and making matzoh with their blood. But it was, of course, the Jews who suffered, paying dearly, with their livelihood and often with their lives, for this absurd belief.

It contributed to our expulsions in the Middle Ages from then-Catholic Britain and still-Catholic Spain. The Eastern Orthodox Russians dabbled in it, so to speak, while czarist authorities mainly repudiated it — until the Menachem Mendel Beilis case in 1911. (A Catholic priest testified, according to the Encyclopedia Judaica, that the crime, the disappearance and alleged murder of a boy, "had all the characteristics of ritual murder enjoined by the Jewish religion." Happily, the Encyclopedia reports that "the jury, composed of simple peasants, … unanimously declared Beilis ‘not guilty.’

The blood libel was used even by the Nazis — who can in no sense be considered Christian. (If they had any religion at all, it is probably best expressed in the phrase wrongly attributed to Dostoevsky’s Ivan Karamazov: "If God is dead, everything is permitted.")

Given that painful history, it is close to miraculous that a pope — particularly this pope, who served in the Hitler Youth — would be visiting a synagogue on the eve of Pesach, where he will be serenaded by its youth choir.

The Catholic Church’s emergence from the dark ages can be traced to the 1965 document Noestra Aetate promulgated at Vatican II, and seems to be continuing. This does not mean that there are no dark passages still to be navigated. The prayer for the conversion of the Jews, for example, though altered, is still troubling. And Time magazine points out that at a Mass in Washington on Thursday — after this newspaper is already in print — the pope was planning to read a "verse from the Gospel of John including Jesus’ offering to his disciples, ‘peace be with you.’ But," Time continues, "that sentence begins, ‘On the evening of that first day of the week, when the doors were locked ... for fear of the Jews.’"

Abraham Foxman of the Anti-Defamation League told the magazine that "he hopes the pope is able to excise those words."

We hope so too.

Dear readers, we wish you a zissen Pesach.