Why is Sukkot celebrated for seven days?
Pesach is a seven-day holiday because the miracle of the Exodus culminated a week after our ancestors left Egypt, with the splitting of the sea and the drowning of the Egyptian army. But for what reason is Sukkot observed as a seven-day celebration?
An answer could perhaps be suggested based on the famous explanation of the Gaon of Vilna (1720-1797) for the Sukkot celebration. According to one view in the Gemara (Sukka 11b), the Sukka that we live in during this holiday commemorates the Ananeh Ha'kabod – the supernatural "clouds of glory" that encircled Beneh Yisrael in the wilderness, protecting them from harm. This is the view accepted by the Shulhan Aruch (Orah Haim 625). The Gaon addressed the question as to why specifically this miracle was worthy of a special Yom Tob, as opposed to the other miracles that G-d performed for Beneh Yisrael in the wilderness, such as the Manna that fell daily from the heavens, and the well that provided water wherever they went. What was special about the Ananei Ha'kabod that warrants a Yom Tob? Another question that arises is why this celebration is held specifically on the 15 of Tishri. How is this date associated with the Ananeh Ha'kabod?
The Gaon of Vilna offered a brilliant answer, noting the chronology of the events following the sin of the golden calf at Mount Sinai. The Sages teach that it was on Yom Kippur, the 10 of Tishri – nearly three months after the people worshipped the calf, on the 17 of Tammuz – when G-d announced His forgiveness for this grievous sin. The next day, Moshe assembled the people and conveyed to them the command to build the Mishkan. Over the next three days – the 12, 13, and 14 of Tishri – the people brought materials for this project, and the construction began the next day, the 15 of Tishri. The Gaon thus explains that in response to the worship of the golden calf, G-d withdrew the precious clouds of glory, as the people were no longer worthy of this special gift. Once they began building the Mishkan, however, He restored the clouds – signifying the complete restoration of His bond of love with the people. Sukkot, then, celebrates not the Ananeh Ha'kabod themselves – but rather the return of the Ananeh Ha'kabod, the fact that Hashem not only forgave Beneh Yisrael for the golden calf, but was prepared to resume His unique relationship with them in response to their genuine repentance.
In truth, however, G-d did more than merely restore His bond with Beneh Yisrael.
Rav Moshe Cordovero (Sefat, 1522-1570), in his work Tomer Deborah, discusses G-d's thirteen attributes of mercy as expressed by the prophet Micha (7:18-20). One of these attributes is articulated through the phrase "Yashub Yerahamenu" (literally, "He shall again have compassion"). The Tomer Deborah explains this to mean that Hashem shows a sinner greater mercy after he performs Teshuba than He did before he committed the wrongful act. Meaning, if one genuinely repents, Hashem does not restore the relationship to what it had been prior to the misdeed – He makes it even stronger. As the Gemara (Berachot 34b) teaches, the pristinely righteous are unable to stand in the place where penitent sinners stand ("Makom She'ba'aleh Teshuba Omedin Sadikim Gemurim Enam Omedin"). Once a person fell into sin, it takes an enormous amount of strength and conviction to change his behavior and repent. Therefore, through genuine Teshuba, one earns even greater closeness to Hashem than He experienced before the sin.
On this basis, we might gain further insight into the celebration of Sukkot. "Yashub Yerahamenu" is the seventh of G-d's attributes of mercy listed by the prophet Micha. Perhaps, then, Sukkot is observed for seven days as an allusion to this unique quality – indicating that on the 15 of Tishri, Beneh Yisrael became even closer to Hashem than they had been before the sin of the golden calf. When G-d restored the Ananeh Ha'kabod, He did more than bring the relationship back to where it had been – He made it even stronger.
This sheds new light on the description of Sukkot in our prayers as "Zeman Simhatenu" – "the time of our joy." There can be no greater joy than recognizing this remarkable quality of Hashem – His willingness to draw even closer to us after we sin than He was before we sinned. His mercy extends so far that He cherishes our efforts to grow and improve even after we've fallen to the lowest depths. As long as we repent sincerely, truly seeking to return to G-d and faithfully serve Him, He not only welcomes us back – but is prepared to bring us even closer than we had been beforehand.