Why did the people of Israel, before their appearance as a nation, first have to endure such terrible slavery in Egypt? The simple explanation is that Israel’s mission is to rectify the moral state of the world, and in order to do so, it must experience firsthand the suffering and the pain that human beings can cause to one another.
Thus, we find several instances where the Torah invokes our experiences in Egypt when instructing us about interpersonal relationships. For example: “You shall not oppress a stranger – for you know the soul of a stranger, since you were strangers in the land of Egypt” (Shemot 23:9) and “If a stranger resides with you in your land, you shall not wrong him. The stranger who resides with you shall be to you as one born among you, and you shall love him as yourself, for you were strangers in the land of Egypt; I am the Lord your God” (Vayikra 19:33-34).
Similarly, the Sages said that before God began to smite the Egyptians, He instructed Moshe to command Israel concerning the mitzva of releasing slaves, so that even before they gained their freedom from Egypt they resolved that once they become free and have slaves of their own, they would never torment them. On the contrary, after six years they would send slaves free and grant them generous gifts (y. Rosh Ha-shana 3:5).
Indeed, an amazing thing happened at the Exodus. All other peoples who overthrew their enslavers became haughty, took power, and enslaved their former masters. Israel, however, did not try to enslave the Egyptians, even after completely defeating them; they only sought their own freedom. This was the first time that freedom appeared in the world as a moral value.
This is why Pesaḥ is called the Festival of Freedom, or, as the Sages termed it in the liturgy, “zeman ḥeirutenu,” “the season of our freedom.” It is no coincidence that Pesaḥ is the first of the pilgrimage festivals: it embodies the foundation of human freedom and consequently of moral responsibility for every individual and societal act. Perhaps this is also why the years of Israelite kings’ reigns were counted from the beginning the month of Nisan, so that the idea of freedom be fundamental to Israelite sovereignty.