Objective and subjective measurements TB Yoma 80

Refraining from eating is one of the five afflictions we observe on Yom Kippur. We are looking for the minimum amount of food that will settle our minds, but not be satiating. The Mishnah says that amount is the size of a date-bulk including its pit. On yesterday’s daf TB Yoma 79 Rabba held that the amount of a date-bulk was larger than the amount of an egg-bulk and Rav Zevid held the opposite view that a date-bulk was smaller than an egg-bulk. I learned today that the halakha follows Rav Zevid. 

Today’s daf TB Yoma 80 elaborates on the topic of measurements. “All the measures in the Torah connected to eating are the volume of an olive-bulk,” (Sefaria.org translation) with two exceptions. The first exception is the amount of food that renders objects tamei, impure or as I like to say ritually unready. Food is not a source of tumah, ritual unreadiness, but a conduit. To transmit tumah the amount of food needs to be the size of an egg-bulk. The second exception is Yom Kippur where the amount of food to trigger the prohibition is a date-bulk.

The next important fact we learned about measurements is its source. “With regard to this topic, Rabbi Yoḥanan said: Measures and punishments are halakha transmitted to Moses from Sinai. The Gemara expresses surprise at this: The punishments for all transgressions are written explicitly in the Torah, and therefore are not part of an oral transmission from Moses. Rather, this is what was said: Rabbi Yoḥanan said: Measures that determine liability for punishments are halakha transmitted to Moses from Sinai.”(Sefaria.org translation)

Last important concept we learn is food has an objective standard whether it is an olive-bulk, date-bulk, or egg-bulk. The measurement concerning liquids is subjective based on the size of the person. A cheek full of liquid is enough to settle person’s mind and trigger the prohibition of drinking on Yom Kippur.

“Rabbi Zeira strongly objects to this halakha with regard to the measure for liability for drinking: What is different with regard to eating, in that all people have the same measure, the volume of a large date; and what is different with regard to drinking, where each and every person is liable according to his own measure, i.e., every individual’s measure depends on the size of his own mouth? Abaye said to him: The Sages have an accepted tradition with regard to the volume of the large date, that eating this amount settles his mind, but less than this amount does not settle his mind. However, with regard to drinking, his mind is settled with the amount of his own cheekful, but his mind is not settled with the cheekful of his fellow who is smaller than him.” (Sefaria.org translation)