Keilim, Chapter 27, Mishnah 2. This chapter deals with fabrics and woven materials, and with the question of how much of such material is needed before it counts as a utensil that can receive tumah. The previous mishnah taught that a piece of cloth that serves a person as something to sit on is subject to tum'at midras, the tumah that a zav or a niddah transmits by pressing their weight on an object. But a scrap of material is not automatically a seat. For it to be considered fit for sitting, and therefore capable of receiving that tumah, it must reach a certain size. Our mishnah sets out those measurements, for cloth and for several other materials as well.
"Habeged mitamei mishum shelosha al shelosha lemidras": woven cloth takes on tum'at midras only once it has reached a square of three by three tefachim. The logic is simple. Anything less than that is too small for a person to rest his weight upon, so it never functions as a seat in the first place, and without a seat there can be no midras.
"Umishum shalosh al shalosh letmei met": for the tumah of a corpse, however, cloth becomes tamei at a far smaller measurement, three fingerbreadths by three fingerbreadths. Here we are not asking whether the piece can be sat upon, only whether it is still useful for something. A scrap that size still has a use for some people, and that is enough to give it the standing of a utensil that can receive tumah.
The mishnah continues with other materials, each with its own measurement, since each is coarser than the one before it and therefore needs to be larger before it is considered useful:
- "Hasak arba'ah al arba'ah": sackcloth, which is woven from goats' hair, receives tumah once it has reached a square of four by four tefachim.
- "Ha'or chamishah al chamishah": leather receives tumah once it has reached a square of five by five tefachim.
- "Mapatz shishah al shishah": matting, woven from reeds or from strips of wood, receives tumah once it has reached a square of six by six tefachim.
"Shavin lemidras uletmei met": in these three cases, sack, leather and matting, the measurement is the same for both kinds of tumah. Whether we are dealing with tum'at midras or with the tumah of a corpse, four by four for sack, five by five for leather and six by six for matting apply equally. There is no distinction in these materials of the sort we found in cloth, where midras requires three tefachim while tumat met is satisfied with three fingerbreadths.
"Rabbi Meir omer: hasak shirav arba'ah, utechilato mishe'yigamer." Rabbi Meir draws a distinction within the case of the sack, between a piece that comes from a finished sack and a sack that is still on the loom. Regarding shirav, the remnants, that is, a piece torn off from a sack that had already been completed, four tefachim by four tefachim suffices for it to receive tumah. Since the sack was once a finished article and served as one, a fragment of that size retains the status of a utensil.
"Utechilato mishe'yigamer": but at its beginning, while the sack is still being woven, the measurement alone is not enough. Even once the weaving has reached four tefachim by four tefachim, the material cannot receive tumah until the weaving is entirely finished. Until then it is not yet a utensil but a work in progress.
The principle emerging from Rabbi Meir's words is that size and completion are two separate requirements. A scrap that comes from something already made and used carries the status of that finished article, and needs only the minimum measurement. A piece that has never yet been finished has no such status, and no measurement will help it until the craftsman completes his work.