One of the central mitzvot of this festival - and the one from which it derives the name Sukkot - is dwelling in a thatched hut called a sukkah. The only source for this can be found in today’s Torah reading:
Speak to the Children of Israel saying, “On the fifteenth day of this seventh month is the festival of Sukkot, seven days to Hashem. . . . In huts (B’SUKKOT) shall you live for seven days. Every native in Israel shall live in huts, so that (L’MA’AN) your descendants shall know that in huts I sheltered (HOSHAVTI) the Children of Israel when I took them out of the land of Egypt. I am Hashem, your G-d” (Vayikra 23:34,42-43).

Upon the Exodus from Egypt, Hashem provided shelter (HOSHAVTI) to the Children of Israel. According to Rabbi Eliezer (Torat Kohanim 17:11 and Sukkah 11b), whose opinion alone is cited by Rashi, this refers to the clouds of glory (ananei ha’kavod) which surrounded the camp, protecting them from wild animals, snakes, scorpions and the elements. Rabbi Akiva, on the other hand, says that HOSHAVTI means that Hashem “housed” His nation in actual huts.

When we leave our permanent homes for the interim shelter of the sukkah we are reminded of our ancestors’ forty year-trek in the wilderness. It is important for us to remember, as Ramban says, “that they were in a desert. They did not enter a house, nor did they find a city for dwelling (Tehillim 107:4), for forty years. Since Hashem was with them, they wanted for nothing.” The sukkah expresses in concrete terms that our security depends, at all times, upon Hashem’s care and protectorship.

This is a significant element of the lessons of the Exodus, arguably the seminal event in Jewish history. Maharal devotes an entire book (Gevurot Hashem) to the centrality of the Exodus to Torah commandments, theology and ethics. As a consequence, he writes (chapter 3), mankind is made aware of Hashem’s Presence in His world. Sukkot, furthermore (chapter 46), highlights the basic human need for shelter, provided by Hashem: “Therefore the commandment of sukkah is for a person to leave his house, which is his place, in order to sit in the shade of the sukkah, because a person needs shelter. Therefore one must dwell in a sukkah, because a sukkah is shelter as well. Understand this well.”

All three Pilgrimage Festivals, therefore, are connected to the Exodus. Torah Temimah (here and on verse 6) writes that, based on Sifra here and Sifri on Devarim 16:11-12, had the Torah not said so explicitly, we might have deduced that eating matzah is also obligatory on Sukkot and living in a sukkah is also obligatory on Pesach! This is because, parallel to matzah on Pesach, the mitzvah of sukkah evokes the Exodus. In contrast, the mitzvah of taking the four species is particular to the season of Sukkot, when the produce is gathered in. Sukkah is the “Exodus mitzvah” of Sukkot.

When R. Yaakov ben Asher (c. 1270-1340) opens the section of the Arba’ah Turim of the laws of the Sukkah (Orach Chaim, ch. 625) he uncharacteristically begins by explaining the intention (kavanah) of this commandment: “This teaches the truth about the Creator’s existence, may He be exalted: He created all by His will, and it is He Who has the power, control and ability in both the upper and lower realms to do as He wishes and there is none to tell Him what to do, as He did with us when He brought us out of Egypt with signs and wonders. The sukkot of which the text says, ‘He sheltered us’ are the clouds of His glory with which He surrounded them so that they would not be smitten by hot wind and sun. Accordingly, He commanded us to construct sukkot so that we remember His wonders and awesome acts…”

R. Yoel Sirkes (1561-1640), in his commentary to Arba’ah Turim, Bayit Chadash, says that it is the “Tur’s” intention to teach a halachah: namely, that one does not fulfill the mitzvah properly unless one keeps in mind its connection to the Exodus while sitting in the sukkah. This is because the verse explicitly says:
Every native in Israel shall live in huts, so that (L’MA’AN) your descendants shall know that in huts I sheltered (HOSHAVTI) the Children of Israel when I took them out of the land of Egypt.

This makes the mitzvah of sukkah unusual: regarding all mitzvot there is the question whether there is an essential need for kavanah (see Berachot 13a, Eruvin 95b, Pesachim 114b). But, that kavanah is no more than the intention to perform a mitzvah. The kavanah of sukkah of which the “Tur” speaks concerns the purpose, the “message,” of the mitzvah.

(In fact, the “Tur” discusses the crucial nature of kavanah in connection with only two other mitzvot: tzitzit (ch. 8) and tefillin (ch. 25). In both instances, “Tur’s” reasoning is based on the fact that the Torah (see Bamidbar 15:40 and Shemot 13:9) mentions explicitly that these mitzvot are to be observed in order to remember, respectively, to do the commandments and the Exodus. It is interesting to note that all three mitzvot introduce the “reason” with the word LEMA’AN.)

These three mitzvot all envelop and surround the person: tefillin on the body, tzitzit on the clothing and sukkah as the shelter. This is reminiscent of the three levels of tzara’at (Vayikra 13:1-59, 14:33-57), which serve as warnings to the sinner. But, when one is entirely embraced by a mitzvah, it is easy to take it for granted, to forget its penetrating message. It is thus all the more vital that we are conscious of the purpose of these mitzvot.

As we sit in our sukkah, let us keep in mind the Exodus when, like a sukkah, Hashem’s sheltering wings first began to enfold us.