LOS ANGELES (CBS) — Passover, which celebrates what the Old Testament describes as God’s deliverance of the Israelites from bondage, begins at sundown Friday amid a call for Southland Jews to reflect on the plague of darkness that God visited upon the land of pharaoh.

Observant Jews will gather for a feast called a Seder, which features six symbolic foods, including matzo, a cracker-like unleavened bread symbolizing the Exodus from ancient Egypt when there was not enough time to let the bread rise. Jews are not supposed to eat anything leavened during the holiday period.

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Bitter herbs, often horseradish, represent the bitterness of slavery; parsley dipped in saltwater symbolizes the tears the Israelites shed in bondage; and an apple, nut, spice and wine mixture called charoset represents what the Hebrew Bible describes as the mortar used by Jewish slaves to build Egyptian edifices.

A number of prominent Jewish scholars, including some rabbis, believe the story of the Exodus is apocryphal and that the Israelites were never among the peoples subjugated by the ancient Egyptians, but they say that should not obscure the themes, including faith and freedom, inherent in the biblical tale.

According to the book of Exodus, the enslaved Israelites used the blood of lambs to mark their doors so the Angel of Death would “pass over” their homes and instead slay the firstborn sons of Egyptians — the 10th and most horrific of the plagues that finally persuaded the pharaoh to agree to Moses’ demand: “Let my people go.”

During the Seder, people drink four cups of wine or grape juice, symbolizing the promises that God made to the Israelites, including deliverance from bondage. Also as part of the ritual, a child traditionally asks “the four questions.”

The introductory question of “Why is this night different from all other nights?” is followed by “Why is that on all other nights during the year we eat either bread or matzo, but on this night we eat matzo?” “Why is it that on all other nights we eat all kinds of vegetables, but on this night we eat bitter herbs?” “Why is it on all other nights we do not dip even once, but on this night we dip twice?” and “Why is it that on all other nights we eat either sitting or reclining, but on this night we eat in a reclining position?”

The meal is accompanied by reading from the Haggadah, or “narration” book, which tells the story of the Israelites’ deliverance from bondage.

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Passover commemorates the time between the Exodus from Egypt on the 15th of the Hebrew month of Nissan and the parting of the Red Sea seven days later.

The holiday is observed for seven days in Israel, with one Seder, and eight days outside Israel, with two. This is because it is held that people in ancient times who lived far from Jerusalem could not know when a new month under the Hebrew lunar calendar had been officially declared and, in turn, could not be sure of the exact date.

In his Passover message to the community, Rabbi Mark S. Diamond, the executive vice president of the Board of Rabbis of Southern California, linked this week’s blackout that left the Mediterranean island nation of Cyprus without power to the ninth plague of the Passover saga, the thick darkness that descended upon Egypt for three days.

“This Passover, take a few moments with family and friends to reflect on the plague of darkness,” Diamond wrote. “Ask yourselves and your fellow Seder participants — who lives in darkness around us? How can we better utilize our resources to alleviate the plagues of injustice and suffering? What can we do to bring light and hope to the dark, lonely corners of the community?”

In a Passover message, President Barack Obama said “the story of the Exodus is thousands of years old, but it remains as relevant as ever.

“Throughout our history, there are those who have targeted the Jewish people for harm — a fact we were so painfully reminded of just a few weeks ago in Toulouse. Just as throughout history, there have been those who have sought to oppress others because of their faith, ethnicity or color of their skin.”

But tonight, he said, “Jews around the world will renew their faith that liberty will ultimately prevail over tyranny. They will give thanks for the blessings of freedom, while remembering those who are not free. And they will ask one of our life’s most difficult questions — once we have passed from bondage to liberty, how do we make the most of all that God has given us?”

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