Many have discussed the nature of Avraham’s sin of asking, “How will I know [my progeny will inherit the Land]”? Avraham speculated whether his children would succeed in handling the gift of the Land in a way that they would live an independent national life in it.
The Seder night is accompanied by songs of freedom, greatness, and malchut, which form a contrast to the situation we could have sunk into had we remained in Egypt, as permanent slaves in the “house of slaves.” We set an atmosphere of “All Jews are the sons of kings” (Shabbat 67a) and “are fit to be kings” (Horiyot 13a).
“This month is for you the ‘head’ of months, the first of the months of the year it shall be for you” (Shemot 12:2). The Mechilta (Bo 1) comments on this: Moshe had trouble telling when the new month was considered to have come … until Hashem showed him the moon as it was renewed and said to him: “See the moon when it is like this and sanctify it.” The nations of the world count from Tishrei; Israel counts from Nisan. We have a tradition that Nisan is the month of liberation: “In Nisan they were liberated; in Nisan, they are destined to be liberated” (Rosh Hashana 11a).
We have always, in times of national success and of national lowliness, celebrated Pesach as the holiday of freedom, in commemoration of the exodus from Egypt. This includes times in which it did not appear that anything was left of that freedom, when the affliction was strong and our nation was drowning in baths of blood prepared by the nations of the world. Even then, celebrating behind sealed windows and drawn blinds, we still continued to teach our children how we were slaves and how Hashem extricated us with a strong and outstretched hand.