As the ten plagues are recited as part of the Passover seder, participants customarily pour a single drop of wine out of their glasses—or remove it with a finger—for each plague. According to the most widespread explanation, the drops of wine are an expression of sympathy at the Egyptians’ suffering, and meant to subtract from the joy of the salvation being commemorated. The real reason for this venerable custom is quite different, however, as Meir Soloveichik explains:
In fact, the point meant to be made by the removal of wine is the exact opposite of what is assumed. One of the earliest documentations of this ritual is that of the 14th-century German rabbi Jacob Moelin, known as Maharil, in his collection of Jewish traditions. We remove the wine, he writes, in order to express our prayer that God “save us from all these [plagues] and they should fall on our enemies.” The drops, in other words, express our desire that the visitation of the Lord’s wrath upon Egypt should happen to others, to every evil empire on earth.
Though we definitely do not delight in the death of innocents who may also have suffered during the plagues, nevertheless the notion that God punishes nations as well as individuals is part of biblical theology, and a desire to see wicked nations punished is bound up in the belief in a just and providential God. “The righteous shall rejoice when he seeeth the vengeance,” the Psalms proclaim, and then the psalmist explains why: “So that a man shall say, Verily there is a reward for the righteous: verily he is a God that judgeth in the earth.”
As to the notion that the tradition reflects a diminishing of joy at this moment, the concept did not make its appearance in Jewish texts until half a millennium later. . .
There are profoundly universalistic elements to the Haggadah. The first part of the seder focuses on Israel and its enemies: “In every generation they rise up against us to destroy us, and God saves us from their hands.” Yet the seder is concluded by emphasizing our shared humanity, looking forward to a time when war will cease. . . . The genius of Judaism lies in its balance of the particular and the universal; indeed, its extraordinary nature consists in its insistence that only through particularism can the universal be appreciated, and only through justice can peace be achieved.