The Torah in Parashat Emor (23:36) introduces the obligation to offer a special sacrifice on Shemini Aseret – the eighth day of Sukkot, which is considered an independent Yom Tob. This refers to the Musaf offering, which the Torah describes elsewhere, in Parashat Pinhas (Bamidbar 29:35-38). In this same verse, the Torah introduces the prohibition against performing Melacha (constructive work) on Shemini Aseret. This holiday is referred to by the term “Aseret,” which literally means “stopping.” The Rabbis explain that we observe this day as though G-d asks us to stay with Him an additional day. After having been together throughout this season of Yamim Tobim, G-d tells us that He finds it difficult, as it were, to part with us, and so we observe an additional day of Yom Tob when we festively celebrate together with Him. Although Shemini Aseret constitutes a separate Yom Tob, and is not part of Sukkot, nevertheless, Jews in the Diaspora eat in the Sukka on Shemini Aseret. This is due to the “Safek” – the uncertainty that Diaspora communities had in ancient times as to when the new month was declared. Given this uncertainty, they needed to consider the possibility that Shemini Aseret was actually the seventh day of Sukkot. Since residing in the Sukka is a Torah obligation, we eat in the Sukka on Shemini Aseret in case this day is actually the final day of Sukkot. Nevertheless, in the prayer service on Shemini Aseret, we mention only Shemini Aseret, and not Sukkot, because this day cannot be both Sukkot and Shemini Aseret. (This situation differs in this respect from that of Shabbat which is also Yom Tob, when we indeed mention both Shabbat and the Yom Tob in our prayer text, since the day truly is both Shabbat and Yom Tob.) Sitting in the Sukka, however, does not contradict the observance of Shemini Aseret, as mentioning Sukkot in the prayers would, since people occasionally spend time outdoors anyway, irrespective of the obligation of Sukka. As Shemini Aseret is the final holiday discussed by the Torah, the Sefer Ha’hinuch chooses this context as the one in which to discuss the prohibition against working on Hol Ha’mo’ed. (This is ironic, as Shemini Aseret specifically does not feature a period of Hol Ha’mo’ed, like Pesach and Sukkot do.) The Sefer Ha’hinuch follows the view of the Ramban and others that working on Hol Ha’mo’ed is forbidden Mi’de’Orayta (by Torah law), and not merely by force of Rabbinic enactment. The Torah did not specify which kinds of work are forbidden on Hol Ha’mo’ed, but instead authorized the Sages to determine which categories of work are prohibited and which are allowed. The Sages established that work is permitted on Hol Ha’mo’ed for the sake of avoiding a financial loss. An exception is the case of work involving a great deal of exertion (“Tirha Yetera”), which is forbidden even to avoid a financial loss, unless one a substantial loss would definitely result from not performing the hard work. Furthermore, it is forbidden to intentionally schedule work for Hol Ha’mo’ed. In ancient times, the rabbinic authorities were empowered to undo work which was scheduled for Hol Ha’mo’ed, such as uprooting plants which were planted in violation of Hol Ha’mo’ed. It goes without saying that one who needs to work on Hol Ha’mo’ed in order to obtain food is permitted to do so. The Rambam disagrees with the aforementioned position of the Ramban, and maintained that work is forbidden on Hol Ha’mo’ed not by force of Torah law, but by force of Rabbinic enactment. In his view, then, if there is some activity whose status vis-à-vis Hol Ha’mo’ed is uncertain, it may be performed on Hol Ha’mo’ed, as we may be lenient in situations of doubt when a Rabbinic law (as opposed to a Torah prohibition) is at stake. In any event, the Sefer Ha’hinuch in this instance does not follow the Rambam’s view, and instead accepts the Ramban’s position, that work on Hol Ha’mo’ed is forbidden by Torah law. The Sages warn us in Pirkeh Avot (3:11)