Meilah, Chapter 4, Mishnah 6. Our chapter has been working its way through a single question asked in many different settings: when do two separate quantities join together to form one halachic measurement, and when does each one stand alone? This mishnah brings two final cases, one from the laws of forbidden foods and one from the laws of tumah.
Orlah and kil'ei hakerem
The mishnah's opening words are "ha'orlah vekhil'ei hakerem," orlah and kil'ei hakerem, and concerning them the Tanna teaches "mistarefin zeh im zeh": the one is added to the other.
Orlah is the fruit that a tree produces during the first three years after it is planted. Kil'ei hakerem is one of the forbidden mixtures: grain or vegetables planted alongside a vineyard, where the produce of that planting becomes prohibited. Neither of these may be eaten.
Now, if a piece of either one falls into permitted food, the standard for bitul, nullification, is unusually demanding. It is not enough to have a simple majority of permitted food; you need two hundred times as much. One orlah apple that falls into two hundred permitted apples is nullified, and the pile may be eaten.
Here is the case of our mishnah. Picture a pile of three hundred and fifty permitted apples. Into that pile falls one orlah apple, and separately one apple of kil'ei hakerem. Measured on its own, each prohibited apple is swallowed up easily: one against three hundred and fifty is far beyond the required ratio, and each would be nullified. But if we count the two together, we now have two prohibited apples against three hundred and fifty, and that is no longer two hundred to one. The whole pile would be forbidden.
That is precisely the ruling of the Tanna Kamma. Even though orlah and kil'ei hakerem are two distinct prohibitions, they are "mistarefin zeh im zeh," they join together, and the combined amount renders the mixture prohibited.
Against this stands the view recorded next: "Ribbi Shimon omer, einan mistarefin." For him the two never merge. Orlah is one issur with its own name, kil'ei hakerem is another issur with a name of its own, and there is no basis for either to contribute its quantity to its neighbor. Each prohibited apple is measured by itself, each is swallowed up in the three hundred and fifty, and the owner may eat the pile.
Four materials, four measurements
Four materials, four measurements
The chapter closes with a set of fabrics and hides that are added to one another with respect to tumah. A piece of clothing that touches an av hatumah picks up that tumah, but only if it is sizeable enough to be reckoned a real article of fabric, and the minimum shiur is not the same from one substance to the next:
Each material needs its own size to be considered a significant utensil, and only then can it receive tumah. The mishnah now asks what happens when two of these materials are attached to one another: "habeged vehasak, hasak veha'or, veha'or vehamapatz, mistarefin zeh im zeh." Cloth with sackcloth, sackcloth with leather, leather with a reed mat, in each of these pairings the two pieces combine with each other.
How much do they need between them? The larger of the two measurements. If cloth and sackcloth are joined, the piece can become tamei once the two together reach four by four tefachim, the measure of the sak. If sackcloth and leather are joined, they must reach five by five, the measure of the leather. And if leather and a reed mat are joined, they must reach six by six, the measure of the mapatz.
Why do they combine at all?
This calls for an explanation. Back in Mishnah 3 we learned as a rule that items with different measurements of tumah do not combine with one another. Why, then, do these four materials join together despite having four different minimum sizes?
"Ribbi Shimon omer, mipnei shehem re'uyin letamei moshav." Ribbi Shimon answers that all four of these materials share one common category: they are all fit to become tamei as a seat. Each of them can contract tumat midras, the tumah that comes when a zav, or another person with that class of tumah, sits, lies, or leans and rests his weight on an object that is designated for that use, such as a chair or a bed. Cloth, sackcloth, leather and reed matting all belong to that group.
Because they share this tzad hashaveh, this common denominator, they are not truly four unrelated substances. They are four expressions of one kind of utensil, and that shared quality is enough to let them combine with one another to make up their minimum measurement.