Those who don't learn from history are doomed to repeat it. So said Thomas Jefferson, and this sentiment has been the basis for the Passover seder for the past 5,000 years of Jewish history. For the modern Jew, remembering history is a way of linking to his or her heritage, and provides a gentle reminder of the blessings and obligations that come with that heritage.
A Picture Worth One Thousand Words
The seder involves two things : one, the reading of the Haggadah, which retells the story of the Jews exodus from Egypt, and the meal itself. The seder plate is arranged in a specific way with foods that represent parts of the story of the exodus. As the Haggadah is read, the reader either points toward the food item, or participants eat the food item, that relates to the portion of the story being related. Participants at a seder literally and figuratively internalize the historic events of their forebears in this way.
For example, the zeroah, or shankbone, represents the lamb that Jewish families sacrificed prior to the visitation by the Angel of Death. The beitzah, a hard-boiled egg, represents the traditional festival offering. Neither of these are touched or eaten by participants, as they are offerings given to G_d.
The maror and chezeret, more commonly known as the bitter herbs, memorialize the bitterness of slavery. The maror is strictly bitter and acrid in its flavor, but the chezeret, generally romaine lettuce fresh from the garden, is bitter at its root, but sweet near the end of the leaf. This represents the transformation in the quality of life as a person moves from slavery toward freedom, and from being constrained in their relationship to G_d to the empowerment of voluntarily obedience to G_d and His laws.
Karpor is a piece of raw onion or boiled potato that is dipped in brine. The salt water represents two significant features from the exodus : the tears shed in captivity by the Jewish slaves, and the brine of the Red Sea. Salt, or brine, is also the way in which traditional Jews kasher or make clean their meats, so the act of going through salt water symbolically has purified the Jew and prepared him or her for life in the promised land.
Charoset is a mixture of apples, walnuts and wine. Its appearance and texture resemble that of mud, which Jewish slaves used to manufacture bricks for the Pharoah. Although its appearance is unattractive, the taste is sweet, once again symbolizing the transformational power of G_d to change bitter, evil circumstances into something good.
Matzoh, of course, is the unleavened bread that the Jews were commanded to take with them on their journey out of Egypt. Matzoh is the food that is most readily associated with Passover.
As a traditional Jew, Jesus celebrated Passover with His adopted family. His seder is commemorated in Christianity as the Last Supper, and rather than reciting the Haggadah, He used the occasion to prepare the disciples for the crucifixion. The symbolism of both events is similar, however. Just as the Passover seder celebrates the liberation of the Jewish people from the oppression of slavery, the Last Supper (now reenacted as communion) celebrates the liberation of the Christian's soul from the shackles of sin to the freedom afforded by amazing grace. Both Easter and Passover celebrate the freedom every person, Christian or Jew, has to choose between good and evil, life and death, and embracing a covenantal relationship with G_d or rejecting His commandments.