When it comes to quantities of food, the rabbis did not use cups and ounces like we do today. Instead, they used common food items to describe the amounts they were talking about. This is all well and good as long as everyone has a similar understanding about the size of common produce and the size of those items remains constant across time and space. Oops.
In the mishnah back on Yoma 73b, we learned that one who eats food that is equivalent to a large date, including its pit, on Yom Kippur, is liable for violating the prohibition of eating on the holiday. On today’s daf, the rabbis consider the question of how large a large date is.
The Gemara initially suggests this answer:
Rava said that Rav Yehuda said: The volume of a large date that they said is larger than an egg-bulk. The sages have an accepted tradition that with this amount of food, the mind of the one who eats is settled, and he is not afflicted. Less than this amount, the mind is not settled.
Rav Yehuda suggests a date and its pit is large if it’s bigger than an egg. But true to form, the Gemara cites an incident that suggests that this statement may not be correct:
An incident happened on the festival of Sukkot. They brought a cooked dish to Rabban Yoḥanan ben Zakkai to taste, and they brought to Rabban Gamliel two dates and a tankard of water. Rabban Yoḥanan ben Zakkai and Rabban Gamliel said to them: Bring them up to the sukkah, and we will eat there. And a baraita was taught in that regard: They did not act this way because that is the halakha, that such food must be eaten in the sukkah. Rather, they wished to be stringent upon themselves and not eat anything outside of the sukkah.
An amount of food larger than an egg must be eaten in a sukkah. But according to this teaching, Rabban Gamliel ate his two dates in the sukkah not because he was required to, but because he was being more strict than necessary. This suggests that the volume of two dates is smaller than an egg.
If both these teachings are correct, we can conclude that two dates are smaller than an egg which is smaller than one large date including its pit. The Gemara finds this hard to believe. Can the volume of a large date and its pit be greater than two pitted dates?
According to the Gemara, it is. Date pits are so big that a large date and its pit holds more volume than two dates without pits. According to a well-known talmudic dictum: “In two kavs of dates there is one kav and more of pits.”
Rav Zedid disagrees with Rav Yehuda, suggesting that the volume of a large date and its pit is less than that of an egg. This is based, in part, upon how Rabbi Yehuda (no relation to Rav Yehuda) reads Deuteronomy 8:10, the verse from which we derive the obligation to recite Grace After Meals: “You shall eat and be satisfied and bless the Lord your God.” For Rabbi Yehuda, it is the experience of satisfaction that triggers the obligation to bless. How much food causes one to be satisfied? According to Rabbi Yehuda, it’s an egg-bulk.
It’s logical to assume that the volume of food that yields satisfaction is greater than that which merely settles the mind. So according to this view, an egg must be bigger than a large date and its pit.
In either case, both Rav Zedid and Rav Yehuda seem to agree that measurements of food are rooted in the effect they have on the one who consumes them. Is this a helpful approach? I’m not so sure. Living in a home with teenagers, I can attest that the amount of food needed to satisfy hunger, or even to settle one’s mind, varies widely by individual.
In the end, neither opinion helps us standardize rabbinic weights and measures. In fact, to this day scholars have a range of understandings of the rabbinic definition of the volume of a date, an olive, and an egg.
In any case, we are not talking here about particularly large quantities of food. My advice? Next Yom Kippur, if you are fasting, avoid food altogether. And if you are interested in the rabbinic conversation about volume specifically, or weights and measures generally, stay tuned — we’ll return to this topic many times before this Daf Yomi cycle is done.
Read all of Yoma 79 on Sefaria.