You arrive home after Kol Nidrei. Even though you had a full meal before you left, you are already slightly hungry and quite thirsty. You open the door to your house to be greeted by a strange sight. The table in the dining room is bedecked with a white tablecloth and adorned with silver Shabbat utensils. The candles flicker in their holders and their shadows dance on the walls. But the familiar aroma of Shabbat food is missing. Even on Kol Nidrei/Friday night, there is nothing to eat.
If they would invent a Mah Nishtanah for Shabbat/Yom Kippur, it would go like this: “Why is this Friday night different from all others? On all other Friday nights we enjoy a festive Shabbat meal. Tonight? No dinner!”
The question is a good one. According to many opinions, it is a Torah obligation to celebrate Shabbat with three festive meals and it is a Torah violation to fast on Shabbat. Why then, do we not postpone Yom Kippur to Sunday like we do with all other fasts?
The most straightforward answer to this question is that the Torah explicitly commands us to fast on the tenth day of Tishrei no matter when it occurs, even on Shabbat. This is similar to brit milah, which must be carried out, notwithstanding the melachah involved, on the eighth day after birth, even if this occurs on Shabbat. As if to emphasize this point, the Torah uses the phrase “be’etzem hayom hazeh” – “on this very day” – both in connection with fasting on Yom Kippur and with brit milah.
In addition to Yom Kippur, there is at least one other instance when a person may fast on Shabbat – the case of a ta’anit chalom, in which a person wishes to fast to prevent an ominous dream from becoming reality.
Interestingly, these two cases are linked. Dreams get mixed reviews in the Talmud. They contain elements of both nonsense and prophecy. Joseph dreams that his father, mother and brothers will one day honor him as king. The nonsense part was that Joseph’s mother was already dead at the time of the dream. The prophetic part was that his father and brothers did subsequently bow down to him. When the people of Nineveh heard the prophecy that their city would be destroyed, they fasted and repented. In permitting a person who has experienced a bad dream on Shabbat to fast on Shabbat, the halacha uses the same terminology we use on Yom Kippur, “likroa et gezar hadin.”
The deeper reason for requiring us to fast on Shabbat/Yom Kippur may lie in the essential difference between Shabbat and Yom Kippur. Shabbat is God’s day of rest. Yom Kippur is ourday of rest. On Shabbat we remain in this world and enjoy the earthly pleasures God created. That is how we acknowledge Him as Creator. Shabbat in this sense is a day of physical rest.
On Yom Kippur, we leave the physical world. We take a day off from the inherent tension caused by the fusion of body and soul. We become pure souls. Yom Kippur is the dress rehearsal of our own yahrzeit. We wear the shrouds in which we will ultimately face Him, and we discard the shoes we will no longer need. By neither eating nor drinking, we celebrate the day like the angels we become. If Shabbat is God’s day off and Yom Kippur is ours, on Shabbat/Yom Kippur God and His people celebrate a day off together.
That Shabbat is a day of rest belonging to the realm of the physical world and Yom Kippur a day of rest belonging to the realm of the meta-physical world seems also to be borne out by the punishment one incurs for performing a malachah on these days. Whereas the ultimate punishment for a melachah performed on Shabbat is death at the hands of a human court, the ultimate punishment for a melachah performed on Yom Kippur is karet, death at the hand of God, or the excision of one’s soul.