Keilim, Chapter 7, Mishnah 5. Our chapter has been dealing with the kira, the earthenware stove, and in particular with the feet on which it rests. An earthenware vessel has a unique law: it contracts tumah when a source of tumah such as a sheretz enters its inner air space, its "avir," even without any physical contact. Since the feet of the kira are treated as part of the vessel itself, the question arises how much of them shares in the kira's status, and what happens when the kira is damaged or built in an unusual way. This mishnah presents four such cases, and in every one of them Rabbi Meir and Rabbi Shimon disagree.
When one foot has broken off
The first situation is introduced with the words "nital echad mehen": a kira normally rests on three legs, and here one of the three has come off, so the stove now sits tipped to one side. Concerning the pair of legs still in place, the mishnah rules "mitame'in bemaga," meaning that a sheretz which touches them renders them tamei, and adds "ve'einan mitame'in ba'avir," that a sheretz suspended inside the hollow of the stove leaves them tahor. Why the difference? A stove missing one leg can still be pressed into service, so touch counts; but since cooking on a kira that leans over is possible only with effort, its inner air no longer transmits tumah to the legs.
Underlying this is a fundamental point about rabbinic decrees. A kira in such a state is no longer properly functional, so whatever tumah it carries here is only derabanan. When the Sages impose a tumah of their own, they deliberately avoid applying it across the board, precisely so that it should not be mistaken for a tumah min haTorah. The practical difference is significant: terumah or kodesh that came into contact with a biblical tumah must be burned, while terumah rendered tamei by rabbinic decree may not be burned. By leaving one avenue of tumah out, in this case the air space, the Sages left a visible marker that the whole matter is rabbinic. This is "divrei Rabbi Meir," the position of Rabbi Meir.
"Rabbi Shimon metaher." Rabbi Shimon holds that the two surviving feet are completely tahor, not even through contact. In his view the Sages never legislated a halfway tumah for earthenware vessels. If they saw no reason to decree tumah through the air space, they equally saw no reason to decree tumah through contact; either the feet are included in the vessel or they are not.
A kira deliberately built on two feet
The mishnah now turns to a second case, a two-footed kira, but one that was made that way from the start: "asah shenayim zeh keneged zeh," he fashioned it with two feet set opposite one another, one on each side. Feet placed this way would be built broader, so that the stove would stand firmly without toppling. Since this is a fully stable, fully usable kira, Rabbi Meir rules "mitame'in bemaga uva'avir," the feet contract tumah both through contact and through the air space. Although a kira on legs normally has three of them, one that was designed with two is a proper vessel, and its feet share its law entirely.
Here too "Rabbi Shimon metaher," Rabbi Shimon declares the two feet tahor.
Feet taller than three fingers
The mishnah now goes back to an ordinary kira resting on its three legs. Earlier we learned the halachah of legs whose height does not exceed three fingerbreadths, which are tamei together with the stove. Here the subject is legs that rise higher than that: "hayu gevohin mishalosh etzba'ot." Such a leg is divided into two portions. The words "mishalosh ulematah" point to the three fingerbreadths measured downward from the stove, that is, the upper part of the leg attached to the kira. That stretch is "mitame'in bemaga uva'avir": it becomes tamei whether a sheretz touches it or hangs suspended in the stove's hollow, because halachah regards it as belonging to the vessel itself.
And the rest of the leg, the length lying farther than three fingerbreadths from the stove? Of that portion the mishnah says "mishalosh ulema'alan," and rules that it is "mitame'in bemaga": a sheretz that touches it renders it tamei, yet "ve'einan mitame'in ba'avir," the air inside the kira does not reach it. Such is the ruling of Rabbi Meir. "Rabbi Shimon metaher": in his opinion whatever lies past those three fingerbreadths is simply tahor, touch included. His approach holds firm through every case in the mishnah: tumah does not come in halves, and therefore the surplus length of the leg carries no tumah at all.
Feet set out from the edge
Some kirot were built with feet that did not stand directly beneath the body of the stove, but were attached at the sides by horizontal bars projecting outward from its base. The mishnah's final case measures how close such feet must be to the kira in order to be included in its tumah through the air space.
The mishnah's language is "hayu meshuchin min hasafah": the legs were pulled back away from the rim, leaving a space between them and the walls of the stove. Whatever falls "betoch shalosh etzba'ot," within three fingerbreadths of that rim, is "mitame'in bemaga uva'avir," tamei by touch and by the vessel's inner air alike. Whatever falls "chutz mishalosh etzba'ot," farther than three fingerbreadths from the rim, is "mitame'in bemaga" but "ve'einan mitame'in ba'avir": touch alone conveys tumah there, while the hollow of the stove does not. Such is the teaching of Rabbi Meir, "divrei Rabbi Meir." There follows "Rabbi Shimon metaher": for Rabbi Shimon, anything standing more than three fingerbreadths away from the rim stays entirely tahor.
Across all four cases, then, the same two approaches emerge. Rabbi Meir is prepared to recognize gradations, extending tumah through contact where the tumah of the air space no longer applies, and thereby signaling that the ruling is rabbinic. Rabbi Shimon rejects any middle ground for earthenware vessels: what is not part of the kira for one form of tumah is not part of it at all.