The Ramban (Rabbi Moshe Nahmanides, Spain-Israel, 1194-1270) makes a fascinating and important comment in Sefer Ha’misvot that directly impacts upon the nature of our annual celebration of Hanukah. He notes a passage in the Gemara which discusses the obligation to give praise to Hashem for bringing us salvation. The Gemara, citing Rabbi Yehoshua Ben Korha, comments, “If for [the rescue] from slavery to freedom they sang praise, then all the more so [is this required when we are delivered] from death to life.” Meaning, if we are obligated to celebrate the Exodus from Egypt, when God delivered us from slavery to freedom, then certainly we are obligated to celebrate when God rescues us from death. The Ramban notes that the rationale of “Kal Va’homer” – that if a Halacha applies in one instance, then it certainly applies in an instance where it is more intuitive – is binding on the level of Torah obligation. If the Gemara deduces through a “Kal Va’homer” that we must celebrate when we are delivered “from death to life,” then this requirement constitutes a Torah obligation.
It emerges, then, that occasions such as Purim, when we commemorate our rescue from death, are celebrated on the level of Torah obligation. Although the specific requirements were instituted by the Sages, and are thus considered obligations Mi’de’rabbanan (on the level of Rabbinic enactment), the concept of making a commemoration is required on the level of Torah obligation.
The Hatam Sofer (Rabbi Moshe Sofer of Pressburg, 1762-1839) extended the Ramban’s principle to the celebration of Hanukah. Although the Greeks did not threaten to exterminate the Jewish people, they did try to eliminate us spiritually. We were not at risk of physical death, but we were at risk of spiritual demise, as the entire Jewish nation was nearly Hellenized. This is an even graver danger than physical death, and therefore, the Hatam Sofer claimed, the celebration of Hanukah constitutes a Torah obligation. The detailed requirements of candle lighting, Al Ha’nissim and Hallel were all enacted by Hazal, but the general requirement to make a commemoration is a Torah obligation. This means that if a person did not make any commemoration of the Hanukah miracle whatsoever throughout the eight days of Hanukah, he has neglected a Torah obligation. Since the requirement to commemorate the miracle is required on the level of Torah obligation, one who fails to make any sort of commemoration is guilty of transgressing Torah law. This notion should give us additional motivation and inspiration to celebrate this holiday properly, realizing that we are bound by Torah law to celebrate the great miracle.
One might, at first glance, ask why, according to the Hatam Sofer, we do not add a ninth day of Hanukah in the Diaspora, just as we add an extra day on other Biblical holidays. We add an extra day of Pesah and Shabuot, for example, because of the doubt faced by Diaspora communities in ancient times regarding the precise date. Why do we not add an extra day of Hanukah, as well, if it, like the other holidays, is required on the level of Torah obligation?
The answer is that, as mentioned, the Torah obligation requires any sort of commemoration; all the details were instituted by Hazal. The requirement to observe specifically an eight-day celebration is a law enacted by the Sages; as far as the Torah obligation is concerned, it suffices to celebrate only one day. Therefore, since the eight-day celebration is required only on the level of Mi’de’rabbanan, we do not add an extra day as we do to the observance of Biblical holidays.