All holidays are collections of cliches, and none more so than Passover, which Jews begin celebrating Friday night. Passover, which commemorates the Jews’ liberation from bondage in ancient Egypt, comes down to us as a dinner, or Seder, with some trusty set pieces: We sing “Dayenu,” we eat matzoh, we drink wine. And that’s all great — it’s hard to quarrel with a holiday that requires you to imbibe four full cups of booze. But what happens when the central message of the holiday, freedom, also becomes a tired metaphor — and a misunderstood one at that?