7. Why was leaven forbidden within Jewish quarters during the seven-day festival, and what did this memorialize?

⁷ During the seven days of the festival, no leaven was to be found in any quarters of the Jews, because leaven represented that which is out of harmony with God, sin. This festival really memorialized that, because of having to leave Egypt in haste, the Israelites did not have enough time to let their dough be leavened. Hence, they had to eat unleavened bread, just as they had done on Passover day.​—Ex. 12:11-34; Deut. 16:2-4.

⁹ “Do you not know that a little leaven ferments the whole lump? Clear away the old leaven, that you may be a new lump, according as you are free from ferment. For, indeed, Christ our passover has been sacrificed. Consequently let us keep the festival, not with old leaven, neither with leaven of badness and wickedness, but with unfermented cakes of sincerity and truth.”

10. Why and how must the antitypical festival be celebrated today, and why can the celebrators be “nothing but joyful”?

¹⁰ That was written about 55 C.E., or 22 years after Christ’s sacrificial death. Today, the spiritual Israelites who read those words of the apostle Paul more than 19 centuries later are duty-bound to keep the antitypical festival, namely, with sincerity and truth.