Shedding some light on the sukkah TB Sukkah 22

Previously we have learned that the purpose of the sukkah is to provide shade. “Any sukkah that is made properly is fit — even though it is not made for the sake of the commandment. And that is so long as it was made for shade” (Mishnah Torah, Laws of Sukkah, 5: 9, Sefaria.org translation) Today’s daf TB Sukkah 22 discusses how much sakhakh must be used to fulfill its mission of providing shade. The Mishnah teaches that the sakhakh must provide more shade than sunlight (שֶׁצִּילָּתָהּ מְרוּבָּה מֵחַמָּתָהּ). The mishnah continues: “A sukka whose roofing is thick like a type of house is fit (kosher-gg).” The second half of the Mishnah seems to contradict the first half and the Gemara provides further explanation.

“The Sages taught in a baraita: With regard to a sukka whose roofing is thick like a type of house, although it is so dense that the stars are not visible from within it, the sukka is fit. However, if it is so thick that the rays of the sun are also not visible from within it, Beit Shammai deem the sukka unfit and Beit Hillel deem it fit.” (Sefaria.org translation)

If you ask any student who has studied the holiday of Sukkot, he/she will tell you that if the rays of the sun are not visible from within it, the sukkah is not kosher. Generally speaking, the halakha follows Beit Hillel and not Beit Shammai. At first glance the halakha seems to be following Beit Shammai!

The Talmud Yerushalmi frames the disagreement between Beit Hillel and Beit Shammai as ex post facto (בדיעבד). They both agree that from the outset (להתחילה) one must see sunlight peeking through the sakhakh. Moses Maimonides in his Mishneh Torah decides “The way of covering is that it be light, in order that the large stars (i.e. the sun-gg) can be seen [through] it. If it was thick like a type of house[roof] — it is fit, even though the stars are not visible.” (Laws of Sukkah, 5:21, Sefaria.org translation)