Rabban Gamaliel did state, "Whoever has not referred to these three matters on Passover has not fulfilled his obligation, and these are they: the Passover [offering], unleavened bread, and bitter herbs. 'Passover'—because the Omnipresent passed over the houses of our ancestors in Egypt. 'Unleavened bread'—because our ancestors were redeemed in Egypt. 'Bitter herbs'—because the Egyptians embittered the lives of our ancestors in Egypt."
In every generation, a person is duty-bound to see him/herself as if he/she personally went forth from Egypt, as it is said, "You shall tell your child in that day saying, 'It is because of what Hashem did for me when I went free from Egypt.'" (Exod. 13:8). Therefore we are duty-bound to thank, praise, glorify, honor, exalt, extol, and the One who made for our ancestors and for us all these miracles, [the One who] brought us forth from slavery to freedom, anguish to joy, mourning to festival, darkness to great light, subjugation to redemption, so we should say before Him, "Hallelujah!"
One of my favorite customs for Shabbat Hagadol is to read the Maggid section of the Passover Haggadah in advance of the first seder. Just as I often feel that I need the second seder to explore all of the great ideas in our retelling of the Exodus narrative, so too does this preview of the ritual meal offer a way to deepen our immersion in liberation consciousness. When given serious attention beyond the seder itself, the Passover Haggadah offers us a message for transforming the way we eat and the way we conduct ourselves every day of the year.
The mishnah above explains how we must meet two very different obligations—one ritual, one psychological—in order to fulfill our duties for the Passover seder. Rabban Gamliel's teaching presents discussing and then eating symbolic foods as the most important part of the seder. Each food item involves midrashic wordplay and also signifies a stage in our people's journey from slavery to freedom. From that relatively concrete approach, the latter part of the mishnah advances a much more abstract requirement that we see ourselves personally as having gone forth from Egypt. While Rabban Gamliel's task is mostly self-explanatory, the subsequent duty begs the fundamental question of how one might accomplish such a feat of spiritual imagination. For that reason, some editions of this mishnah and of the Haggadah record the obligation as one of outward demonstration as well as inner contemplation.
Indeed, both parts of this mishnah address a combination of inner and outer expressions of gratitude for our redemption from bondage, a theme that Jewish Food Movement advocates have highlighted as our heritage's unique contribution to discussions of food security and sustainability, global poverty, and injustice. We must heed the charge of our Haggadah—"Let all who are hungry come and eat!"—as a call to action for true social change.