The vast majority of Jewish festivals follow the famous pattern: They tried to kill the Jews; we survived; let’s eat! Put that way, it is an oversimplification, and yet it’s fair to say that the emotional timbres of Jewish festivals are tied up with our national memory.

On Pesach, we’re thankful that we were freed from Egypt. On Shavuot, we’re thankful that we received the commandments. On Purim and...