Ohalos, Chapter 16, Mishnah 1. Until now we have been dealing mainly with structures and coverings that are fixed in place. Our mishnah turns to portable objects, and it teaches us that even an ordinary object a person carries around can serve as an ohel that carries tumah from a meis to whatever else lies beneath it. Along the way we will meet one of the sharpest disagreements in Shas about how a halacha was misreported, and how Rebbi Akiva stepped in to make peace between the two sides.
The opening ruling
The mishnah begins: "Kol hametaltelin mevi'in es hatumah ke'ovi hamardeya." Metaltelin are movable items. Picture such an item stretched out so that one end of it is positioned above a meis and the other end is positioned above keilim. The mishnah rules that this object functions as an ohel: the tumah rises from the meis, travels along beneath the object, and descends upon the keilim on the far end.
What thickness does the object need? The mishnah's standard is "ke'ovi hamardeya," the girth of a mardeya. Ovi means thickness, and ke'ovi therefore means as thick as. The mardeya is familiar to us from Maseches Keilim: it is the long stick with which a plowman jabs his ox so that the animal keeps pulling in the proper direction. This is hardly a heavy beam. Its shiur is defined by its perimeter: wrap a string once around the pole, and the string comes to a tefach.
A tefach around, or a tefach across?
Think about what such a figure yields. Suppose the string that encircles the pole measures no more than a tefach; how wide is the pole itself? A familiar ratio governs this: a circle whose perimeter is three tefachim has a diameter, the straight span across its middle, of one tefach. Imagine a perfectly round lake. If you walk its shoreline until you arrive back where you began and that walk takes three miles, then a swim straight across the water from bank to bank covers only a mile. Accordingly, a mardeya whose entire perimeter amounts to one tefach measures merely one third of a tefach in width.
An obvious question arises. Over and over we have been taught that nothing counts as an ohel unless it presents a square tefach of covering. Yet here the roof spread above the tumah spans one third of a tefach. How can the mishnah hold that so thin a rounded stick carries tumah from the meis at one edge to the keli at the other?
The Bartenura answers, at this stage of the mishnah, that this is a gezeirah derabbanan. The concern of Chazal was that people would confuse the circumference with the diameter. Tell someone that a certain lake measures three miles, meaning three miles all the way around, and someone else will report that the lake measures one mile, meaning one mile straight across. Which is it, one mile or three? Different people will quote different figures, because they never grasped which measurement was being described.
Return now to our stick. By Torah law, had one edge of this goad hovered above a meis while the opposite edge hovered above a keli, no tumah would cross over, since the necessary width is absent: we have only one third of a tefach. But imagine a man hurrying to his rov: part of my goad was above a meis and part of it was above my keli, has the keli become tamei? The rov inspects the stick, finds it one third of a tefach across, and rules the keli tahor. The bystanders will leave believing that even a tefach poses no difficulty, for it never registered with them that the tefach under discussion described the perimeter, while the span across the stick came to no more than one third of a tefach, which is precisely why the rov was lenient. Mimeila, Chazal issued a decree: wherever a tefach is in play, even a tefach of perimeter, the tzibbur should be trained to treat the situation as one of tumah.
Rebbi Tarfon's protest
Rebbi Tarfon rejected this, and not in a mild way. "Akapach es banai shezo halacha mekupachas." He swore, in effect, that he would be cut off from his children, because this reported halacha is itself a cut off halacha, that is to say, a mistake. Rebbi Tarfon maintained flatly that an ohel does not convey tumah unless it has the width of a tefach.
The language is extraordinarily strong. The Tosfos Yom Tov, citing Rashi, explains what stood behind it. Rebbi Tarfon was gripped by dread at the thought that Torah was being forgotten and garbled, and that terrible tza'ar burst out of him in these words.
What really happened in the beis medrash
Rebbi Tarfon goes on to trace the source of the error: "sheshama hashomei'a," a listener heard a ruling and misreported it. A question had been brought to the beis medrash and the answer given was tamei, and someone who overheard it never grasped what the case actually was.
What had actually taken place was this. "Shehaya ikar over": an ikar is a plowman, and this plowman was passing by on the road. "Vehamardeya al keseifav": his goad lay across his shoulder. "Vehe'el tzido ha'echad," one edge of it formed a roof, "al hakever," above a grave, as he went along. The she'eilah was whether the man himself had become tamei. The beis medrash answered that he was, "vetim'uhu," but the grounds were "mishum keilim hama'ahilim al hameis": the plowman was in physical contact with a keli, this very goad, and that keli was itself spread over a meis.
Notice the gap between the two cases. In the mishnah's opening scenario nobody is holding the pole whatsoever: one edge rests above the meis while the far edge rests above a keli or above a person, and the assertion is that tumah ascends from the meis, runs beneath the covering the pole creates, and settles on whatever lies at the opposite end. The plowman's case was nothing of the sort. His goad was borne on his shoulder, so he was touching it, and it is undisputed that whoever touches a keli spread over a meis contracts tumah, even if that keli is thinner than a tefach. The man who overheard the psak was clearly only half attentive, and he went off publicizing that a plowman had inquired about a goad with one edge over a grave and its far edge over himself, and that the rov declared him tamei although the pole did not have a tefach of width. That was never what the beis medrash said.
Why seven days?
Lema'aseh, the farmer was told that he was tamei for seven days. That itself needs explaining. If his tumah came from touching the mardeya, which had become tamei by overshadowing the meis, he should be no more than a rishon letumah, and a rishon letumah is tamei only for that day. Why seven?
The Bartenura directs us to the halacha of tumah bechiburin, which came up in an earlier mishnah: a person or keli that touches something bearing tumas meis at a moment when that something has not yet been separated from the meis is regarded as though he had touched the meis directly. Others attribute the seven days to cherev harei hu kechalal: a metal blade resting on a meis becomes an avi avos hatumah in its own right. There is a machlokes, though, whether this principle operates only when the metal is literally on the meis, or applies as well when it merely forms a covering over it.
Either way, insists Rebbi Tarfon, the popular version is a mistake. Whatever the reason the farmer was declared tamei, it was certainly not because he stood under a shared ohel narrower than a tefach. There is no such halacha. An ohel less than a tefach wide does not spread tumah.
Rebbi Akiva makes both sides stand
"Omar Rebbi Akiva, ani asaken." Rebbi Akiva declares: I will set this straight. I will present the case so that the ruling of the chachamim can stand exactly as it was given, "sheyihyu divrei chachamim kayamim." Rebbi Tarfon is right, and the halacha as originally transmitted is right as well. All that is needed is precision about what the case really was.
As a rule, teaches Rebbi Akiva, Rebbi Tarfon's position holds. Nobody mixes up perimeter with width, and there is no basis for treating a stick as an ohel simply because a string around it reaches a tefach while the span across it does not. One case alone is different: where a man bears the portable item on his shoulder while it stands over the meis. We may assume his shoulder is covered; he has on a shirt or a coat. His beged is mafsik, coming between his flesh and the wood. In such circumstances we do rule that the plowman becomes tamei.
Now work out the reckoning. Strictly speaking his tumah should last for the day and not for seven. His flesh is in contact with the garment, and the garment carries the status of av hatumah, because the garment rests against the item that overshadows the meis. What makes the garment an av? Two possible routes. One is tumah bechiburin: as long as the goad is stationed directly over the meis, anything touching the goad shares the goad's own rank. The other is cherev harei hu kechalal: the goad poised above the meis is then an avi avos hatumah, and the garment touching it descends one rank to av hatumah, since a person or keli touching a chalal becomes an av hatumah. Either way, his flesh, which touches the garment, is a rishon letumah, and a rishon letumah is tamei for that day alone.
But here Chazal had a genuine worry. The next day this man handles terumah or eats kodshim, onlookers protest that he is tamei, and he answers that his tumah lasted only one day. Nobody in the street will grasp that his one day tumah stemmed from his skin touching his garment. They will conclude instead that a person standing under a movable object that overshadows a meis is tamei for a single day. The report will travel, and eventually someone whose round pole genuinely is a tefach wide will be told: what is the problem? I heard of exactly such a case; you were under a pole and the pole was over a meis, so you are tamei only for the day, I know this befeirush. He will never know that in the original case the pole was not a tefach wide, that the tumah there came not from ohel at all but from contact, and that the contact was not even direct, since it was his beged that lay against the mardeya. The confusion would be total.
Therefore Chazal decreed: even an object whose measurement around and around is merely a tefach, though its width from side to side falls short of a tefach, if a person is actually in contact with it, carrying it on his shoulder as it passes over the meis, then although the chain from pole to shirt to skin should leave him no more than a rishon letumah, we treat him as tamei for seven days.
The words of Rebbi Akiva
Look inside his words once again. "Kol hametaltelin mevi'in es hatumah," all movable items convey tumah, "al adam hanoisen," upon the person who bears the item, "be'ovi hamardeya," with nothing more than a goad's thickness. Normally, standing beneath a stick that is thinner than a tefach and lies over a meis leaves a man tahor. But if he is the one shouldering that stick while its far edge crosses over the meis, then although the stick lacks a whole tefach of width and attains a tefach only in its perimeter, tumah is brought upon him. And instead of a tumah that expires with the day, we pronounce him tamei for seven.
Follow the objections as they come. Why is he tamei, the pole is less than a tefach? Because he is touching it. He is not touching it, it rests on his shirt. Then he is tamei because his skin touches the shirt that touches the pole that overshadows the meis, and that should make him only a rishon letumah, tamei for the day. Correct. Strictly he should be tamei for the day alone; but to head off the confusion that would follow, since the public will never reconstruct what actually happened, we rule seven days.
So Rebbi Tarfon is right: as a matter of tumas ohel, the mere fact that an object lies above the meis and above a person does not make him tamei if it lacks a tefach of width. And the beis medrash was right too: when the pole rests on his shoulder and he is in contact with it as it passes above the meis, he does become tamei, by force of a gezeirah derabbanan. That is what the Tanna Kamma of our mishnah meant: there is a special decree rendering him tamei for seven days where by right he should be tamei only for the day.
The keli itself
The mishnah appends one more clause: "ve'al atzmon bekolshehu." Observe precisely where the width requirement operates. Only tumah that rises into the ohel and then travels on to something else demands a square tefach of covering. For the keli itself to become tamei while it hangs over a meis, no minimum applies at all: "bekolshehu," it turns tamei no matter how slender it is. The width matters exclusively "ve'al she'ar adam vecheilim," regarding additional people and additional keilim situated under this movable item that overshadows the meis; there the demand is "befosei'ach tefach," that the covering overhead hold a full tefach in each direction.
Summary and halacha
Let us gather the strands. The opening opinion maintains that even where Torah law generates no tumah whatsoever, the width falling short of a tefach, Chazal nonetheless imposed tumah. Rebbi Tarfon holds that tumas ohel does not pass through any covering that lacks a tefach. Rebbi Akiva concurs in principle that a covering thinner than a tefach transmits nothing, but holds that a decree was made in one narrow case: a man carrying on his shoulder a keli thinner than a tefach while that keli stands directly above a meis. In strict terms his tumah should expire with the day, since his flesh touches the keli that overshadows the meis. There, to forestall the misunderstanding that would otherwise spread, Chazal declared him tamei for seven days. Finally the mishnah teaches that the keli, however thin, does contract tumah when it hangs over a meis. All the discussion of a square tefach, and whether or not to decree, bears only benogeia transmitting tumah to another person or keli lying under the stick that overshadows the meis.
Lahalacha, the Rambam rules in accordance with Rebbi Akiva. Picture a man entering the beis medrash with a she'eilah: I was carrying a keli and one of its ends passed above tumah, what is my status? The rov's first question will be whether a string around the keli comes to a tefach. It does, the man replies, but its width falls short of a tefach. Does the perimeter genuinely reach a tefach? Yes. Then unfortunately you are tamei miderabbanan, since Chazal decreed on anything with a tefach of perimeter, lest it be confused with something a full tefach wide. And for how long? Seven days. As for the other keilim that lay beneath the far end, they stay tahor, and another man who was standing under it likewise stays tahor. Absent a real width of a tefach, no one positioned below the stick becomes tamei. The only one to become tamei is the man bearing it, and this is Rebbi Akiva's shitta.