Via Brad DeLong, I found a year old post in which Mark Kleiman comments on Passover and Jewish law in
Avodim hayyinu l'Pharoh b'Mitzrayim:
That, then, is the deeper meaning of the first phrase in the answer to the Four Questions at the Passover Seder: "Avodim hayyinu" -- "We were slaves."Passover really is an amazing holiday. The symbolism of the Seder is so careful, and the oral tradition so carefully preserved. The Seder is a ceremony which reminds Jews every year that they are free people, and that their freedom did not come easily.
It seems, if you think about it, a rather remarkable assertion to put at the very center of a celebratory feast. What other group, instead of boasting about being nobly born, makes a fuss about being descended from slaves, and then personalizes it so as to say that everyone present was a slave until redeemed?
But linked to the commandments in Deuteronomy, that phrase comes to mean: "We were slaves" and therefore must never, never, ever act like slaveowners. That makes sense of the empirical link between Judaism and liberalism.
We sit in the most comfortable chairs, eat charoset, drink, chat and have fun, because we are free, and freedom is sweet. But there are the bitter herbs which we dip in salt water to remind us of the sufferings of our slavery and the tears our people spilled. It's not uncommon for people at a Seder to read from the Declaration of Independence, or the "I Have a Dream" speech.
It's a celebration of freedom, a Thanksgiving of sorts, but also a mourning for the past. On Passover, you cannot turn someone away from your door. You open the door, so no one need go hungry. You set an extra place at the table, just in case. You remember those less well off.
Why is this night different from all other nights? If we learn the lessons of the Seder, it isn't because we think of those less fortunate.
Here's something else to think about. There are several sets of brothers in the Torah. Cain and Abel, Jacob and Esau, Isaac and Ishmael, Moses and Aaron. All but the last fought. I wasn't until the brothers found a way to serve their God together that the Jewish people could complete their covenant, becoming people of the law. There's a lesson there.
"Once we were slaves."
Slaves to the Pharaoh, but slaves also to hate between brothers. There's a lesson there.
“Mirele” by Chava Alberstein from the album Foreign Letters (2001, 2:38).