Mishneh Torah, Rest on the Tenth of Tishrei 2

Sugya Map

• Issue: Definition of the shiur (measure) for liability on Yom Kippur—specifically the divergence between food (k'kotevet) and liquid (m'lo lugmav).
• Nafka Mina: Liability for karet and malkot when consuming suboptimal amounts or non-food substances.
• Primary Sources: Yoma 80a, Yoma 81a, Mishneh Torah, Rest on the Tenth of Tishrei 2:1.

Text Snapshot

Rambam states: "All foods [that one eats] are combined... similarly, one who drinks a cheekful... Foods and liquids are not combined in a single measure."

• Nuance: The Rambam insists on a "large ripe date" (k'kotevet) for food, rejecting the standard k'zayit used elsewhere in the Torah. The dikduk here is crucial: he defines the date as "slightly less than an egg," anchoring the halacha in a physical, functional capacity of the throat rather than a mere arbitrary volume.

Readings

• Sefer HaMenucha: Argues that the shiur is grounded in the psychological state of mit'yashva da'ata (satiation). Even an "Og, King of Bashan" is liable for a date, because the shiur is a universal standard of satiety.
• Tzafnat Pa'neach: Notes that liability on Yom Kippur isn't just about "eating" in the technical sense, but about the nature of the act. If the substance is "fit for human consumption," it negates the innui (affliction) of the day, triggering liability.

Friction

The Kushya: If the shiur for all prohibitions is generally k'zayit, why does Yom Kippur demand k'kotevet? The Terutz: The Gemara Yoma 80a clarifies that k'kotevet is the threshold where a person’s appetite is actually sated. Anything less is a "defective" act of eating that fails to disrupt the mandatory innui.

Intertext

The distinction between food and liquid is echoed in Shulchan Aruch, Orach Chayim 271:13, where the cheekful measure is debated. This highlights a broader heuristic: halachic measures are often functional (based on human capacity) rather than purely mathematical.

Psak/Practice

In modern practice, when a sick person must eat on Yom Kippur, the Mishnah Berurah (Orach Chayim 618:3) mandates eating pachot-pachot (less than the shiur) to minimize the transgression. This relies on the Rambam’s assertion that food and liquid don't combine; by spacing out the consumption, one avoids reaching the shiur in a single k'dei achilat pras.

Takeaway

Yom Kippur liability is defined by functional impact (satiation) rather than arbitrary volume. To "afflict" oneself is to starve the appetite; therefore, the shiur is exactly the amount required to satisfy it.