Keilim, Chapter 8, Mishnah 1. Here begins the chapter's treatment of tum'ah as it applies to vessels of clay, and the opening case raises a basic conceptual issue: if a person erects a barrier across the interior of a clay vessel, splitting it into two halves, do we now count two vessels, or does the halachah still see a single vessel that happens to have a wall standing inside it?
The background to remember is the special rule of klei cheres. An earthenware vessel becomes tamei when a source of tum'ah, such as a dead sheretz, enters its inner air space, even without any contact at all. And once the vessel itself is tamei, food lying in its air space becomes tamei as well. Everything in this mishnah revolves around the question of what counts as being "inside" that air space.
An oven divided down the middle
The mishnah begins: "Hatanur shechatzatzo banessarim o bayeriot" - an earthenware oven that was partitioned off with wooden boards or with curtains. The picture is of a person who ran a divider from the top of the oven straight down to its floor, splitting the oven into two compartments, one on each side of the wall.
"Nimtza sheretz bimkom echad": should the carcass of a sheretz turn up on one side of the barrier, then "hakol tamei", the whole oven together with all its contents contracts tum'ah, food resting on the far side included. Halachically the barrier achieves nothing. One cannot convert a single clay oven into a pair of ovens by erecting a wall within it. It stays one large keli, and the halachah proceeds precisely as though nobody had ever put up a divider.
A broken basket hanging in the oven
A broken basket hanging in the oven
A second case now follows, a different attempt at separation which likewise fails to split an earthenware vessel in two. "Kaveret pechutah upekukah bekash": a woven basket in which a sizeable hole had opened, the hole having been blocked with straw. This basket is "umshulshelet la'avir hatanur", lowered down into the oven's hollow, so that it dangles within the oven while its own sides encircle whatever has been placed in it.
"Hasheretz betochah, hatanur tamei." Should the sheretz be lying within the basket, the oven contracts tum'ah, and this despite the fact that the basket's sides currently surround the sheretz on every side. What is the reason? This basket does not qualify as a vessel at all. A wide hole has opened in it, and the only thing sealing that hole is straw, which constitutes neither a true mending nor a true stopper. Not being a valid keli, it cannot serve as a valid barrier either, and the sheretz is viewed as lying openly within the oven's interior.
"Hasheretz batanur, ochalin shebetochah tme'in." Reverse the positions and the identical reasoning applies. When the sheretz lies in the oven, the oven contracts tum'ah from it, and food resting in the suspended basket becomes tamei as well, for that food counts as lying within the hollow of a tamei clay oven. That the basket's sides encircle the food makes no difference, since a basket with a hole patched by straw does not constitute a barrier.
Rabbi Eliezer's kal vachomer
"VeRabbi Eliezer metaher." On the case of the damaged basket Rabbi Eliezer dissents and declares it tahor whichever way the case runs. He holds that the basket's sides, broken and straw plugged though they are, do screen off its interior from the hollow of the oven, so that anything within the basket is simply not situated in the oven's inner air. Consequently, a sheretz resting in the basket leaves the oven tahor, and a tamei oven leaves food inside the basket tahor.
Rabbi Eliezer supports his ruling with an argument: "Im hitzila bemet hachamur, lo tatzil bichli cheres hakal." If a basket of this sort shields its contents where the tum'ah involved is that of a corpse, the stringent case, surely it shields them where we are dealing with the far lighter tum'ah of a clay vessel. Corpse tum'ah is the gravest tum'ah in the Torah, and a mishnah in Ohalot teaches that such a basket's sides, sealed with nothing more than straw, do protect what lies within from tum'at met. Given that it succeeds there, Rabbi Eliezer reasons, it must certainly succeed in the easier case of a keli cheres. On its face the kal vachomer looks compelling.
The Rabbis' answer
The Rabbis' answer
"Amru lo": the Chachamim responded that the inference fails. Granted, the basket rescues its contents from the grave tum'ah of a corpse, but the reason is that the halachah of tents allows a space to be carved up into distinct areas: "sheken cholkin ohalim." Within the laws of ohalot internal compartments are recognized, so a barrier there generates a genuinely independent space. Regarding clay vessels the opposite holds, "she'ein cholkin klei cheres", and hence their question: "tatzil bichli cheres hakal"? Earthenware admits no division whatsoever, just as the mishnah stated at the very start: put up a wall inside an oven and you have not produced two ovens but one oven containing a wall.
So the fact that clay vessel tum'ah is the lighter case turns out to be beside the point. The analogy breaks down not on account of corpse tum'ah being weightier, but because the very mechanism Rabbi Eliezer leans on, partitioning off a space by means of a barrier, is a feature of the halachot of tents and has no counterpart in the halachot of clay vessels. A keli cheres knows nothing of internal compartments, and on that basis the Chachamim dismissed the kal vachomer and held that both a sheretz in the basket and food in the basket are reckoned as being in the oven's hollow.