It is well-known that in the year in which they left Egypt the tenth of Nissan was a Shabbat. Therefore "the Shabbat preceding Pessach is called the Great Shabbat [Shabbat HaGadol] because of the miracle that occurred on it" (Shulchan Aruch, Orach Chayim, 430:1). The Mishna Berurah (#101) explains: "For in the year in which they left Egypt the tenth of Nissan was a Shabbat and every member of Israel took a lamb for his Pessach [offering] and tied it to his bedpost, as it says, 'Speak to the entire assembly of the children of Israel saying: On the tenth of this month, they should take for themselves, every man a lamb according to the house of their fathers etc" The Egyptians saw this and asked them what it was for. They answered: To slaughter as a Pessach [offering] in accordance with the command that Hashem has placed upon us. And they [the Egyptians] gnashed their teeth over the fact that they were slaughtering their gods, but they were unable to say anything to them. Since the tenth of Nissan was on that occasion a Shabbat they instituted that every Shabbat preceding Pessach should always be called Shabbat HaGadol." Many have asked that according to this reason the tenth should have been the designated date even if it falls on a weekday, rather than the Shabbat.
 
Rav Charlap (in his commentary on the Haggadah) writes: "All that Hakadosh Baruch Hu wished for was to reveal the permanent holiness of Israel, for despite all the masks and disguises they still retained an inner holiness. This Divine point is revealed when they are drawn away from and detach themselves from those things that resist it (=that lead them astray from that inner sanctity). They are therefore commanded, 'Draw and take for yourselves sheep for your families and slaughter the Pessach' - 'draw your hands from idolatry' (Mechilta). As soon as they draw away from idolatry the Holy Spirit descended upon them and they attached themselves to the Living God. Through the mere denial of idolatry their lofty attachment is already revealed because that guarded point was never dulled and extinguished." This means that in order for Am Yisrael to be revealed in actuality, it must uncover its pure roots, which were hidden in Egypt. Idol worshipping forms the absolute antithesis to the pure Israelite life. Therefore, so that Am Yisrael should be worthy of redemption they must draw themselves away from the idolatry in which they were submerged. An action such as this demands great spiritual strength, and only through a connection to the original and permanent holiness of Israel can they detach themselves from the seductive force of idol worshipping. When they were successful in this and took themselves away from idolatry the independent Israelite sanctity was openly revealed. This action was performed on the tenth of Nissan at the moment when they took the lamb for the Pessach offering. The lamb, the Egyptians' god, was taken to be slaughtered in the name of the service of Hashem. Therefore, it is only at the Pessach in Egypt that Israel was already required to take the offering on the tenth, in order that they should be worthy of the redemption.
 
It is most suitable that the connection to the pure Israelite source should take place on a Shabbat. Rav Charlap proceeds to explain: "Hence their taking on the tenth was on a holy Shabbat, for the sanctity of Shabbat is fixed and permanent and there is no need for Israel to sanctify it." Shabbat expresses the Divine sanctity revealed through time, and is not dependant on our actions (as opposed to the sanctity of festivals, in which Israel must sanctify the month, and only in such a manner does the festival occur). Although the sanctity of Shabbat is fixed and permanent, we are nonetheless commanded to sanctify it, as it states, "Remember the Shabbat day to sanctify it," the pasuk from which we learn the commandment to make kiddush [sanctification] on Shabbat. Thus while the sanctity of Shabbat is an original one, and is independent of us, we are still commanded to reveal it. This is exactly the same as we explained above regarding the sanctity of Israel. This is the meaning of our words in the morning prayer on Shabbat: "And You did not give it, Hashem our G-d, to the nations of the lands, and You did not give it as an inheritance, our King, to those who worship molten images, nor may the uncircumcised dwell in His rest, for You have given it in love to Israel Your people, to the descendants of Ya'akov, whom you chose." Due to Israel's original sanctity, the original sanctity of Shabbat, and the inner compatibility between them, Israel received the command regarding the Shabbat. When Israel keeps the Shabbat, the Divine sanctity is revealed in its various aspects, and Israel fulfills its function in the world.

According to this we can understand why the date was fixed as "Shabbat HaGadol" rather than the tenth of Nissan. Pessach is the festival of freedom, freedom from the outer forces that cover our pure root. On Pessach we are commanded to connect in reality, in an open and palpable manner, to our Divine source. Shabbat is undoubtedly the most suitable day for this demand. According to this, the festival of Pessach commences on the Shabbat preceding it, for only in this manner are we able to fulfill the commandment of "And you shall tell your sons" in a complete fashion. We are not commanded to take the lamb on the tenth of Nissan every year, however, because it is not a permanent situation, baruch Hashem, that Israelites worship idolatry, as opposed to the positive command to connect to the original holiness, which is always with us.
 
The Rambam (Laws of Chametz and Matzah, 7:2) writes: "It is a mitzvah to tell the sons even if they have not asked, as it says, 'And you shall tell your sons.' A father teaches his son according to the latter's capacity for understanding. How so? If he is young or stupid he says to him: We were all slaves like this maidservant, or like this servant, in Egypt, and on this night Hakadosh Baruch Hu redeemed us and we went out to freedom. If the son is older or wiser he tells him what happened to us in Egypt and the miracles that were performed through Moshe Rabbenu, all according to the son's understanding." The central mitzvah of Seder night is the telling of the exodus from Egypt to the children, each child according to his understanding. It is clear that a person who has young children is neither required nor able to delve into the exodus in any depth, but must rather tell the story as it was. He must make use of "gimmicks" in order to encourage the children to listen: "And changes must be made on this night in order that the children will see and ask, What is different?...Until we answer them, such and such occurred, and such and such happened. How does he make these changes? He divides out grains of corn and nuts, they remove the table from in front of them before they eat, and they snatch from one another, and the like" (Rambam, ibid, 13). The question is asked: Would not an educated and intelligent person feel frustrated that it is on this wonderful Seder night that he is required to occupy himself with children's stories instead of being able to deal with the themes of freedom, the Pessach offering etc in depth?

According to our above explanation, however, the matter is clear. The purpose of the Pessach festival is to reveal the pure Israelite root and through this to try to express in actuality this Divine foundation. Each year on Seder night we are required to relive the exodus from Egypt, along with all the spiritual meaning that was revealed at that time. The main point of Seder night does not lie in intellectual analysis, but rather in the natural flow of our Israelite selves. Hence the central focus of the mitzvah of the telling of the story of the exodus is linked to the children - "And you shall tell your sons." As is known, children are sensitive to falsity, and if we tell them a story without truly living it, they would immediately sense this. They will begin to get bored and to disturb and will eventually develop resistance to our teachings (these ideas are correct regarding children's educational as a whole. If parents and educators merely pay lip service to their beliefs and it is all only a "show," it should come as no surprise when children rebel against their parents' ways. First of all, parents must be internally and deeply attached to their beliefs and then, with G-d's help, they will be successful in educating their children).

This is what the Mishnah in Pesachim (116b) states (and we also say it in the Pessach Haggadah): "In each and every generation a man must see himself as if he left Egypt, as it states, 'And you shall tell your son on that day saying: For this Hashem acted for me when I left Egypt'" (xiii, 8). The Mishnah learns from the pasuk "for this Hashem acted for me..." that everyone must feel as though he left Egypt. But it is no coincidence that the first part of the pasuk reads "And you shall tell your son on that day..." When you tell your son the story of the exodus from Egypt, you will reach the state that you yourself are at this moment leaving Egypt. This is why the editor of the Haggadah adds: "Not our fathers alone did Hakadosh Baruch redeem, but He redeemed us too along with them."
 
In the Pessach Haggadah we say: "The Torah spoke of four sons: One wise, one wicked, one simple, and one who does not know how to ask." We will focus exclusively on the wicked son. "What does the wicked [son] say? - 'What is this service to you?' (xii, 26), 'to you' and not to him. Since he separated himself from society he is a heretic." In the following pasuk (27) the Torah states: "And you shall say, It is a Pessach sacrifice to Hashem, who passed over the houses of the children of Israel when He smote Egypt, and He saved our houses..." Yet this answer which appears in the Torah is not the answer for the wicked son that appears in the Haggadah. There it states: "You too should blunt his teeth and say to him, 'For this Hashem acted for me when I left Egypt.' 'For me' and not for him; had he been there he would not have been redeemed." This answer is the one for the son who does not know how to ask, and it was removed from its place and given to the wicked son. A perusal of the pasukim resolves this difficulty. The pasuk states: "And you shall say, It is a Pessach sacrifice to Hashem"; it does not state: "And you shall say to him." This formulation implies that there is no direct answer for the wicked son. When a wicked person asks argumentative and provocative questions, there are occasions on which he must immediately be cut off and have "his teeth blunted." This is in order to shock him, as well as to forestall his possible influence on others. While this is only the immediate answer, we must be worried by the fact that there are children such as this among Am Yisrael. Aside from those children, it says something about us as well. If we were living the pure Israelite life in an internal and true manner, its light would shine on that wicked person as well, and he too would become part of a life of Torah and holiness. When this is not the case, we must examine our own carefully. The Torah therefore states: "And you shall say, It is a Pessach sacrifice to Hashem" - state it to yourselves first of all. We must return and live the redemption of Israel, and sense deeply how Hakadsh Baruch Hu passed over the houses over the children of Israel. Hakadosh Baruch Hu caused His Shechina to rest on all the houses of Israel, where the offering is eaten on Pesach, and if so we are truly the Shechina's chariot. This is the deeper answer for the wicked son. There is no doubt that this answer's influence will only be effective after a long period has elapsed, yet this is the answer that will truly have a profound result. These matters connect to all that we explained above regarding the issue of Seder night.

We are situated in the middle of difficult struggles, the more painful of which are the struggles between ourselves. We are sure that the more we continue to live by the internal Divine content of Am Yisrael in depth and purity, the Divine light will be increasingly revealed, and will lighten up the path of the entire nation.