That’s an excellent question, worthy of being asked by the “Wise Son”!
God made four promises to the Jewish People describing our Exodus from Egypt and our birth as a nation: “I will take you out; I will save you; I will redeem you; I will take you as a nation.” (Ex. 6:6-7) All of these promises were kept.
Based on this, our Sages instituted a rabbinical mitzvah to drink four cups, corresponding to these four promises.
What do these four promises actually mean? The Maharal of Prague explains that the transformation of our being slaves in Egypt to a free nation with a special connection to God involved four separate and distinct stages. The four promises correspond to these four stages.
1. Freedom from “cruel and unusual” labor. This came as soon as the plagues were introduced.
2. Freedom from being slaves. This occurred after the final plague.
3. Freedom from being in a foreigner’s land. This took place when they crossed the Red Sea and left Egypt.
4. Freedom to become a nation with a special connection to God by receiving the Torah at Mt. Sinai.
We recite Kiddush over the first cup, we read the Exodus story from the Haggadah over the second cup, we recite the Grace after Meals over the third cup, and we sing the Hallel Psalms of praise to God over the fourth cup.
Enjoy leading the Seder and I wish you a Happy Passover as well!
