Parshas Bo begins with a command, now the urgent time has come when events will come together to finally bring Israel's Egyptian slavery to an end. Yet before they leave, the Jews are expected to slaughter a sheep, the Korban Pesach. Unlike the Matza, which resulted when unleavened dough did not have time to leaven because of the speed with which the Jews had to leave Egypt, the Korban Pesach was eaten at leisure. In fact it was forbidden to eat it quickly.
What is the difference between the Korban Pesach and the Matza, both of which were obligations that one had to perform on the Seder night of the first day, or one had not fulfilled his paschal obligation.
During the Haggadah we say, "Korban Pesach Zu Al Shum Ma, Al Shum shePasach Hakadosh Baruch Hu..." What is this Paschal regarding, because the Holy One Blessed Be He passed by our houses when he came to slay the Egyptian first born. What is the significance of the entire event. Why the first born and why the lamb and the blood that marked the doors of the houses.
Did G-d not know otherwise which of them were Jews and which were Egyptians? To the contrary, G-d had demonstrated repeatedly that even with the earlier plagues, very fine distinctions could be made between Egyptian and Jew. There would be darkness for one and not the other. Hail for one and not the other. Wild animals for one and not the other. Certainly this night was no different.
Why then was this night different from all other nights and why were the First Born different from all others? To begin with, let us answer the question of why a lamb. The Jews had come to Egypt as shepherds, an abomination to Egyptians who worshiped the sheep. The Jews ate lamb, the Egyptians did not, so when the brothers visited Joseph, the Egyptians would not eat what they ate. So too when Pharaoh suggests that Moshe and the Jews bring their offerings to G-d in Egypt, he points out that they could not slaughter the deity of Egypt, and not be slaughtered themselves by the Egyptians.
Yet on this night everything changed. On this night, the Korban Pesach, whose service would involve the participation of a Kohen (though it could be slaughtered by anyone) but then involved the Jewish First Born, would be slaughtered inside Egypt itself. And while that happened the Egyptian first born who had led the service would be slain by G-d himself. The blood of the lamb would mark the doors of Jewish homes to demonstrate their rejection of the idolatry that had pervaded Egypt. By this act, the Jews demonstrated their difference vs the Egyptians, so that when the angel of Egypt at the sea complained, "These are idol worshipers and these are idol worshipers," the Korban Pesach was G-d's reply.
This was why the Korban Pesach was the first Mitzvah given and why the month of Nissan is also the first month. For Tishrei which contains Rosh Hashana is the month that marks the calendar's progression, as accepting G-d as king is required before we can proceed onward, but Nissan is counted as the first month, as before accepting G-d, we must first abandon the worship of all other things.
By killing the gods of Egypt, the Jews demonstrated that they were prepared to make a clean break with all that Egypt represented, and only then could they go free.
This too is why the Korban Pesach took place at leisure, with four days to prepare for it, and an extensive meal, for it is the groundwork that has to be completed before the redemption can happen, which is a slow process. But when that is done, the redemption itself can happen in an instant, which is symbolized by the Matza, the dough that had no time to leaven.
In Galut today, we do not have a Korban Pesach, or the means to lift ourselves up properly, and so we cannot do what we must. Instead we have the Matza, the waiting for that instant of redemption in which without warning, the world will change around us.