We have learned that one of the five forbidden, pleasurable activities on Yom Kippur is eating. The Mishna (73b) taught that in order to be held liable for eating, one must consume an amount of food the size of a kotevet ha-gasa – a large date. Since this measurement is an unusual one (for example, with regard to birkat ha-mazon – grace after meals – the minimum amount that needs to be eaten is either a ka-zayit – the size of an olive – or a ka-beitza – the size of an egg), the Gemara on our daf attempts to define it.
Rava quotes Rav Yehuda as teaching that a kotevet ha-gasa must be larger than an egg, since the Sages determined that only an amount greater than a ka-beitza size gives a sense of satisfaction. While ordinarily the Sages do not attempt to give explanations for the specific size requirement given by the Torah, Rabbi Avraham Tiktin, in his Davar Be-ito argues that in this case there was a recognition that the rules of Yom Kippur were left to the Sages to define (see the Ran’s explanation of this phenomenon on page 73b), so we must try and understand their underlying logic.
In an attempt to examine Rava’s position that a kotevet ha-gasa must be larger than an egg, the Gemara brings a series of stories about the Sages and their eating habits. A baraita records that when asked to taste the food that was being cooked on Sukkot, Rabban Yohanan ben Zakkai insisted that it be brought into the sukka, as did Rabban Gamliel when he was brought two dates with water. Both Rabbis knew that the food that they had been brought did not really need to be eaten in the sukka, but they were stringent on themselves, and insisted that any food that they ate could only be eaten in the sukka.
In contrast to these Sages, the baraita also tells of Rabbi Tzadok who would eat less than a ka-beitza of food by wrapping it in a napkin and eating it outside the sukka without an after-blessing. Rabbi Tzadok’s behavior is subject to a difference of opinion between Rashi who says that he took the food in a napkin because of his fastidiousness, while Tosafot explain that his religious devotion was such that he treated all food as though it were teruma, so he refrained from touching food lest it become ritually defiled. In any case, it is clear that the baraita tells Rabbi Tzadok’s story in order to emphasize that just as there were Sages who were stringent upon themselves, there were also those who made a point of emphasizing that it was appropriate to stick to the letter of the law without stringencies. In this story, Rabbi Tzadok was lenient with regard to sukka, ritual hand washing and the blessing after food.