Keilim, Chapter 17, Mishnah 11. The mishnayot before this one taught that when the Sages set a shiur using a natural object, such as an olive, an egg or a pomegranate, they intended the medium specimen of that species, not the unusually large one and not the unusually small one. Our mishnah now turns the corner and presents a second category: measures where the Sages deliberately intended the smaller version. From there the mishnah moves to a third category altogether, measures that have no fixed size at all because they are gauged by the body of the particular person involved.
Measures where the smaller version is intended
The mishnah's opening words are "V'yesh she'amru b'midah dakah", there are instances in which the Sages had in mind the fine, that is, the reduced standard. Which instances? "Midot halach v'hayavesh", the units used for measuring liquids and the units used for measuring dry produce. "Shiuran b'Italki", the quantity intended is the one current in Italy, "zo midbarit", and that Italian unit is precisely the one that served the nation during its years in the desert.
The practical application concerns the measures we meet in the service of the Beit Hamikdash. When the Sages speak of a hin, the liquid measure used for the wine of the nesachim, or of an isaron, the dry measure of flour brought as a minchah, they mean the smaller of the versions in which those units existed.
Why should there even be more than one version of a hin or an isaron? Here lies the difference between this mishnah and the ones before it. An olive, an egg and a pomegranate are natural objects, and their size varies with the produce itself, with the year and with the place, which is why the Sages had to tell us to take the average specimen. Liquid and dry measures are not natural at all. They are the product of a declaration: society decides how much liquid fills a hin and how much flour fills an isaron. And because they rest on a declaration, they were able to change in the course of history.
At the time the Torah was received in the desert, a hin held one particular volume of wine and an isaron one particular volume of flour. At a later stage the chachamim ruled that these units be expanded, and in Yerushalayim each of the pair was raised by a fifth above its desert size. Another such ruling was issued in Tzipori, adding a further fifth on top of the Yerushalayim figure. Our mishnah therefore settles which of the three sizes is meant when a hin or an isaron is mentioned: the one that Italy still preserved in the era of the Tannaim, the smallest of the three, identical to the unit in use in the desert when the Torah was given.
Measures that go by the individual
The mishnah now opens a third heading. "V'yesh she'amru", there is yet another class of measures, and of these the Tannaim taught "hakol l'fi mah shehu adam", the entire reckoning goes according to what the person himself is. Such shiurim carry no uniform figure whatsoever. They are subjective, rising and falling with the dimensions of the body of the one performing the act, and the mishnah proceeds to list them.
"Hakometz et haminchah", the removal of the kometz from a flour offering. The three middle fingers are folded down against the palm, and the flour trapped beneath them is exactly what constitutes the kometz taken from the minchah. Its volume is therefore nothing other than a reflection of how large that particular kohen's hand happens to be.
"V'hachofen et haketoret", and the one who scoops the ketoret with cupped hands. This refers to the Kohen Gadol on Yom Kippur, who would join his two hands together, scoop up as much ketoret as they could hold, and bring it in to burn in the Kodesh Hakodashim. There is no fixed quantity here either; the amount is whatever his two hands contain.
"V'hashoteh k'milo lugmav b'Yom Hakippurim", and one who drinks a cheekful on Yom Kippur is liable for violating the prohibition of drinking. Once again the shiur is measured against the person's own mouth rather than against any standard vessel.
The two meals of the eruv
The mishnah now brings a further measure that some hold depends on the individual: "U'chimzon shtei se'udot la'eruv", and like the food of two meals for an eruv. A person may walk two thousand amot on Shabbat in every direction from his place of residence. If he wishes to shift that radius, he deposits the food of two meals at a spot before Shabbat, and that spot becomes his residence for this purpose, so that he may walk two thousand amot in every direction from there. According to this view the quantity of food is not fixed; it follows how much each particular person normally eats.
"Mezono l'chol aval lo l'Shabbat": the reckoning goes by his ordinary daily food and not by his Shabbat food. The figure sought is what he consumes over two of his weekday meals, rather than what he consumes over a pair of meals eaten on Shabbat. "Divrei Rebbi Meir", such is the ruling of Rebbi Meir. "Rebbi Yehudah omer: l'Shabbat aval lo l'chol" takes the reverse position: the Shabbat meals furnish the yardstick, and the weekday meals do not.
The mishnah then discloses that neither Tanna is arguing for stringency: "Elu v'elu mitkavnim l'hakel", the aim of both is leniency, namely, to demand the lesser quantity of food for the eruv. Each is simply describing the eating habits familiar to him. Rebbi Meir knew a pattern in which the Shabbat table is the more generous one, since the food of Shabbat is flavorful and there is oneg Shabbat; a plain weekday meal accordingly involves less food, and it is that lesser quantity he adopts as the standard. Rebbi Yehudah knew a pattern in which any single Shabbat meal turns out to be the more modest one, since Shabbat carries three meals, seudah shlishit included, and there is a limit to what one can consume in the course of a single day, so the food is spread thinner over each meal; that is why he gauges the eruv by Shabbat.
The Tannaim who fix an objective amount
Other Tannaim in the mishnah hold that the chachamim did establish a set quantity for the two meals of the eruv, one that does not vary from person to person.
"Rebbi Shimon omer: mishtei yadot lakikar mishalosh l'kav", Rebbi Shimon says: two thirds of a loaf, of the sort where three loaves are produced from a kav of wheat. A kav is twenty four egg volumes, so each such loaf contains eight egg volumes, and two thirds of that loaf comes to five and a third egg volumes. That is his objective shiur for the two meals.
"Rebbi Yochanan ben Beroka omer" supplies a different figure: "mikikar b'pundeyon", "me'arba'ah se'in b'sela", a full loaf whose price is a pundeyon (a coin of small value) in a period when a sela buys four se'ah of wheat. Working out that calculation produces eight egg volumes.
So this mishnah has carried us through three distinct kinds of shiurim: the declared measures of liquid and dry volume, where the Sages meant the original small wilderness measure still preserved in Italy; the personal measures such as the kometz, the two handfuls of ketoret and the cheekful on Yom Kippur, which are read off the person's own body; and the two meals of the eruv, where Rebbi Meir and Rebbi Yehudah measure by the individual's appetite, each aiming for leniency, while Rebbi Shimon and Rebbi Yochanan ben Beroka fix a standard amount for everyone.