Menachos chapter 6, mishnah 5. In this mishnah we will deal with two topics: in its first half - how the flour is produced from the raw grain, and in its second half - how the minchah is divided into loaves.
Producing the fine flour from the grain:
The mishnah says: "Kol hamenachos te'unos shelosh me'os shifah v'chamesh me'os beitah" - all the menachos require three hundred rubbings and five hundred poundings. Two processing actions are required for the grain:
Shifah - rubbing the grain three hundred times: one takes his hand and rubs the kernels on a clean surface, in order to remove the chaff - that hard, fibrous, inedible material surrounding the kernel of wheat or barley.
Beitah - pounding five hundred times. Although the word usually means kicking, here it refers to pounding done with the heel of the hand, the lower, hard part of the palm, in order to prepare the grain properly and turn it into flour.
How do we arrive at the numbers three hundred and five hundred?
There is a fixed rhythm for the rubbing and the pounding, made up of a single cycle: one rubbing and two poundings, and afterward two rubbings and three poundings. The total of the cycle is three rubbings (one plus two) and five poundings (two plus three). When the cycle is repeated one hundred times, the result is three hundred rubbings and five hundred poundings - and this is what the mishnah means.
To what do the rubbing and the pounding apply - to the wheat kernels or to the dough?
The mishnah continues: "V'shafah u'v'atah bachitim" - and he rubs and pounds the wheat kernels; that is, the rubbing and the pounding are done to the wheat kernels themselves, and not to the kneaded dough. Whereas "Rabbi Yosei omer: af babatzek" - Rabbi Yosei says: also in the dough - the dough too requires rubbing and pounding, three hundred and five hundred times respectively. This is how the mishnah reads as we have it, and this is also the version of Tosafos, based on a different beraisa.
However, the Rishonim disagree about this:
The Bartenura: the word "also" does not belong here, and therefore there is a dispute between the tanna kamma and Rabbi Yosei as to which of the two the rubbing and the pounding apply to: according to the tanna kamma - to the kernels, and according to Rabbi Yosei - to the dough.
The Rambam: according to his version, the rubbing applies both to the kernels and to the dough, while the pounding applies to the dough alone.
The halachah was ruled like Rabbi Yosei, and as the Rambam understood it.
Dividing the minchah into loaves:
The Mishnah now turns to the stage at which the mixture of the minchah is prepared: an isaron of fine flour and a log of oil, from which the dough is made (and sometimes water is added as well, all depending on the type of minchah). The mass of dough is not made into one large loaf; rather, it is divided into a series of loaves, cakes or wafers, according to the type of minchah. The question is into how many loaves it is divided.
Two possibilities emerge from the verses:
Twelve loaves - the minchas chavitin, the daily offering of the Kohen Gadol, which is made as twelve loaves: half in the morning and half in the afternoon. And likewise the lechem hapanim, twelve loaves that rest on the Table from week to week.
Ten loaves - the loaves of the todah, which accompany the thanksgiving offering with forty loaves of four types, ten loaves of each type. And likewise the offering of the nazir, which is accompanied by twenty loaves of two types, ten loaves of each.
It emerges that the verses specified certain menachos that are made as ten loaves and certain menachos that are made as twelve. The question is what the law is regarding the rest of the menachos, which were not spelled out in the verses: a person who volunteers to bring a minchas soles, a marcheshes, a machavas or a maaseh tanur - into how many loaves is his minchah made, ten or twelve? This is the subject of the dispute of the Tannaim in our Mishnah:
Rabbi Yehudah: "Kol hamenachos ba'os eser eser, chutz milechem hapanim vachavitei kohen gadol shehen ba'os shteim esreh" - always ten loaves, and only these two menachos are exceptions to the rule, since regarding them the verse explicitly stated twelve.
Rabbi Meir: All of them come as twelve loaves, "chutz mechalos todah vehanezirus shehen ba'os eser eser" - only these two offerings are accompanied by loaves that are divided into ten.
The reasoning behind the dispute:
Rabbi Yehudah holds that when we come to derive the law of the rest of the menachos, it is fitting to learn from the loaves that come with the todah and with the nazir, since these are similar in their essence to the other menachos and the manner of their preparation parallels theirs. This is not the case with the lechem hapanim and the shtei halechem, which are the most exceptional among the menachos: they do not go up on the Altar and no kemitzah is taken from them. Why should we learn from those unusual menachos, when we can learn from the ordinary and comparable menachos of the todah and the nazir?
Rabbi Meir, on the other hand, holds that although there is reason not to learn from the todah and from the nazir, since these menachos are exceptional in that they are kodashim kalim - eaten by the owner who brings them and by his friends - the ordinary menachos are kodshei kodashim, and they are judged by an entirely different standard. Therefore we should learn specifically from the minchas chavitin of the Kohen Gadol and from the lechem hapanim, which are also kodshei kodashim like the rest of the menachos.
In summary: We learned that all the menachos require three hundred strokes of shifah and five hundred strokes of betishah, performed in a fixed cycle repeated one hundred times, and the Rishonim disagreed as to whether these actions apply to the kernels, to the dough, or to both - and the halachah follows Rabbi Yose, as the Rambam understands it. We also learned of the dispute between Rabbi Yehudah and Rabbi Meir regarding the division of the minchah into loaves, and the halachah follows the first opinion, that of Rabbi Yehudah: all the menachos are made as ten loaves, and the only ones made as twelve loaves are the lechem hapanim and the minchas chavitin of the Kohen Gadol.