There is a mitzva to rejoice on all the festivals, as the Torah says, “You shall rejoice in your festival” (Devarim 16:14). On Sukkot, though, we are to be extra joyful. Therefore, the mitzva to rejoice on all the festivals was stated in context of Sukkot:
After the ingathering from your threshing floor and your vat, you shall hold the seven-day festival of Sukkot. You shall rejoice in your festival, with your son and daughter, your male and female slave, the Levite, the stranger, the fatherless, and the widow in your communities. For seven days you shall hold a festival for the Lord your God, in the place that the Lord will choose; for the Lord your God will bless all your crops and all your undertakings, and you shall have nothing but joy. (Devarim 16:13-15)
Similarly we read, “Mark, on the fifteenth day of the seventh month, when you have gathered in the yield of your land, you shall observe the seven-day festival of the Lord…and you shall rejoice before the Lord your God seven days” (Vayikra 23:39-40).
Joy is not explicitly mentioned in context of Pesaḥ. The Sages explain that this is because Pesaḥ is the time of judgment for the grain for the upcoming year. Additionally, since many Egyptians died then, our joy is incomplete. In reference to the festival of Shavu’ot, joy is mentioned once: “Then you shall observe the Festival of Weeks…and you shall rejoice before the Lord your God” (Devarim 16:10-11). By this point of the year, we already know that the grain has grown, and we are happy about it, but we are still worried about the rest of the produce. The word “joy” is not used in reference to Rosh Ha-shana, because it is a time of judgment for the entire world. But on Sukkot, after all the grain and fruits have been gathered in, and after we have repented and been atoned, we can truly and completely rejoice. This is why the verses speaking of Sukkot mention rejoicing three times (Pesikta De-Rav Kahana, Sukkot; Beit Yosef, OḤ 490:4; MB ad loc. 7).
The extra joy of Sukkot, then, is an end-of-year celebration, marking the ingathering of all the year’s produce – a material and spiritual ingathering of grain and fruits as well as of everything we learned and all the good things we did during the year. This ingathering is especially pure since it follows the season of repentance and atonement (as explained in section 2 above). The mitzva of taking the lulav also expresses the joy of the material and spiritual ingathering (section 3 above). Thus, we are elevated toward the Source of Life in ecstasy, and we gather to celebrate before the Lord our God. The sukka, surrounding us on all sides, symbolizes the ingathering of all the good things we did during the year. They all come together perfectly and envelop us, bathing us in divine light.
When we gather together every aspect and degree of goodness, even those which seem at first glance to be incompatible with one another, God spreads His canopy of peace over us, and Israel becomes cohesive and unified. For as long as each element stands on its own, there is no unity. But on the ingathering festival, all elements come together, revealing their unity. This is the meaning of the Sages’ statement: “All Jews can sit in one sukka” (Sukka 27b). Similarly, the four species hint at the different types of Jews who come together on Sukkot (below, 4:2-3).
Through the relative perfection that we attain on Sukkot in this world, we will reach the greater perfection in the messianic future, as the Sages said: “Of one who fulfills the mitzva of sukka in this world, the Holy One says, ‘He fulfilled the mitzva of sukka in this world; I will shelter him from the intense heat of the days to come’” (Pesikta De-Rav Kahana, Sukkot). This echoes a statement from the Gemara:
There will be no Gehinnom in the future. Rather, God will remove the sun from its sheath and intensify its heat. The wicked will be brought to justice by it, and the righteous will be healed by it. The wicked will be brought to justice by it, as it is written: “For lo! That day is at hand, burning like an oven. All the arrogant and all the doers of evil shall be straw, and the day that is coming – said the Lord of Hosts – shall burn them to ashes…” (Malakhi 3:19-20). The righteous will be healed by it, as it is written: “But for you who revere My name, a sun of victory shall rise to bring healing” (ibid.). Moreover, they will delight in it, as it is written: “You shall go forth and stamp like stall-fed calves” (ibid.). (Avoda Zara 3b)
The Sages tell us that the mitzvot which we perform in this world become garments that will allow us to absorb the great light in the future (Zohar II 210a). The sukka expresses this in our world, as it is the mitzva and shield that allows us to absorb the great light in a manner that is appropriate for us. (See the end of section 4.)
