Passover commemorates the Exodus from Egypt, Shavuot commemorates the giving of the Torah, and Sukkot commemorates God’s providence, from desert times until the present day. These festivals also correspond to the agricultural seasons in the Land of Israel. This is why Passover is also called the Spring Festival, Shavuot the Harvest Festival, and Sukkot the Ingathering Festival. At these times, especially in agricultural societies, people are naturally happy. In the spring, we are happy because of the rejuvenation of the crops after the bleak winter. During the harvest, we are happy because of the abundance of blessing in the crops. During the ingathering, we are happy because of the variety of produce we have been blessed to gather.
We are commanded to elevate and sanctify these naturally joyful feelings and connect them to the spiritual processes taking place in the supernal worlds. Passover takes place at a time of beginning and renewal, hence we left Egypt then and became a nation. Shavuot takes place at a time when the growth process reaches maturity, hence that was when we received the Torah. Sukkot takes place at a time of joyful celebration of bounty, at the culmination of the year’s agricultural endeavors. Therefore, this is when we express our great joy that the Divine Presence rests upon us, and give thanks for all the positive things which result from living under God’s supervision.
The festivals are also days of heavenly judgment. On Passover, judgment is passed on grain, determining how much will grow until the late spring. On Shavuot, judgment is passed on fruit, determining how much will grow during the summer. On Sukkot, judgment is passed on water, determining how much rain the Land of Israel will receive in the winter. On Rosh Ha-shana, judgment is passed on all people. God has given us an opportunity to reconnect with Him joyfully and thankfully at each season, thus ensuring blessing for the next season as well.