Ohalos, Chapter 1, Mishnah 3. The first mishnayos of this masechta are occupied with measuring the reach of the tumah of a meis: how many stages it can pass through, and what degree of tumah settles on each stage. Here the count arrives at four, and Rabbi Akiva then proposes a case of five.
Reviewing the shorter chains
Some cases stop at two. Reuven lays his hand on a corpse; afterwards Shimon lays a hand on Reuven. Reuven has become an av hatumah with a seven day tumah, while Shimon has nothing more than tumas erev, tumah that lifts at nightfall, making him a rishon letumah. The chain has exhausted itself already at two.
Other cases reach three. Begin with a keli that comes into contact with a meis. The corpse holds the rank of avi avos hatumah, and a keli which touches it does not drop a step; it acquires that very same rank of avi avos hatumah. Should that keli then meet a second keli, the second one is an av hatumah, and it too carries tumah for seven full days. If a person, or another keli, then makes contact with that second keli, it holds tumah only for the day, since whatever meets an av hatumah falls to the level of rishon letumah. That is three.
Keitzad arba
The mishnah poses the question: "Keitzad arba?" By what route does tumah reach a fourth stage away from the corpse? The reply: "Keilim nog'in bemeis." Once more the starting point is a keli in contact with the meis. The pasuk teaches that a human being who comes up against a corpse steps down to av hatumah, whereas a keli in that same position steps down not at all; its rank equals the corpse's own, avi avos hatumah.
Then "ve'adam bekeilim": a man lays a hand on that keli, and he becomes an av hatumah. Then "vekeilim be'adam": keilim come into contact with that man. Here lies the mishnah's chiddush. Those keilim do not fall to rishon letumah at all. Their rank stays av hatumah, "temei'in tumas shiv'ah," a tumah lasting seven days.
It is worth dwelling on this. According to the mishnah, the first set of keilim, having met the corpse, hold the rank of avi avos hatumah; the man who took hold of them holds the rank of av hatumah; and the second set of keilim, which he in turn handled, hold the rank of av hatumah as well. Yes, that is exactly what is being taught.
Only now does the chain lose its strength: "veha-revi'i," the fourth stage, "bein adam bein keilim," be it a man or a keli making contact with those keilim which the man had handled, "tamei tumas erev," is a rishon letumah whose tumah ends when evening comes.
Set the four side by side. First, the keli in contact with the corpse. Second, the man who took hold of it. Third, the keli he then took hold of. Fourth, whatever man or keli comes up against that third item. And the sole reason a fourth stage exists at all is the chiddush found at the third: keilim in contact with an av hatumah hold their ground and keep a seven day tumah.
The source in the pasuk
From where does all this come? The Torah writes: "Kol horeg nefesh vechol noge'a bechalal... techabesu vigdeichem bayom hashevi'i ut'hartem," launder your garments on the seventh day and become pure. Now consider whom the phrase "kol horeg nefesh," anyone who has taken a life, is added to cover. It cannot be describing one who came in contact with the body, since that case is stated separately in the words "noge'a bechalal." The picture must therefore be this: a man slew another with a sword. Since the blade met the body, the blade is an avi avos hatumah, and consequently the man gripping it is an av hatumah. And the Torah's instruction for him? His garments require sprinkling on day three and day seven, and laundering on the seventh.
Now, a count of seven days belongs to an av hatumah alone. If this man's garments are drawn into a seven day procedure, the conclusion is that keilim which have handled an av hatumah bear tumah for seven days themselves. Nor is this limited to the clothes on his back; the same holds for any keli whatsoever. Hence the fresh rule: keilim which encounter an av hatumah retain the rank of av hatumah. That is precisely what makes room for a fourth stage.
Let us run through the sequence one final time. The corpse: avi avos hatumah. The keli which met it: still avi avos hatumah. The man who then took hold of that keli: down a step, av hatumah. The keli he took hold of, and this is our chiddush: av hatumah once again. And finally, just as with anything that comes up against an av hatumah, the fourth item, adam or keli, is a rishon letumah whose tumah expires at nightfall.
Rabbi Akiva: yesh li chamishi
"Omar Rabbi Akiva: yesh li chamishi." Rabbi Akiva announces that he has a case in which tumah still lands on a fifth stage removed from the corpse. What is he after? One further extension away from the meis that nonetheless draws some degree of tumah.
His case: "hashapud hatachuv ba'ohel." Picture a tent with a corpse lying within, and a pole planted in the tent that props up its roof. "Ha'ohel vehashapud," the tent together with the pole, "ve'adam hanoge'a bashapud," plus a man who lays hold of the pole once the body has been carried out of the tent, "vekeilim be'adam," plus keilim that come up against that man: all of them, "temei'in tumas shiv'ah," bear a seven day tumah. And thereafter, "hachamishi, bein adam bein keilim, tamei tumas erev": the fifth item, adam or keli, has tumah for the day only.
Count out his chain. Number one is the tent, an avi avos hatumah because it houses the body. Number two is the pole holding it up, likewise avi avos hatumah. Number three, once the body has been taken away, is the man who lays hold of the pole; he steps down to av hatumah. Number four are the keilim that come up against him, which by the rule just established stay at av hatumah. Number five is a man or a keli meeting those keilim, and that one drops to rishon letumah, tamei until the evening.
Now read the list backwards: an adam or keilim met keilim; those keilim had met a man; the man had grasped a pole; the pole was set in a tent; the tent sheltered a corpse. Tent, pole, man, keilim, and one more after them. Those are Rabbi Akiva's five.
The Chachamim's answer
"Omru lo." The Chachamim replied that the count here is not five, because "ein ha'ohel mis'chashev": the tent does not enter the tally as a stage of its own. Rabbi Akiva has reckoned the tent first and the pole second, as though the pole picked up its tumah from the tent. Not so, say the Chachamim: the pole was never rendered tamei by the tent, but on its own account, for the mere fact that it stands within an ohel that shelters a corpse.
Here is the proof. Imagine the tent were built of a substance incapable of receiving tumah, so that the tent itself never became tamei. The pole would be tamei all the same, since it stands inside an ohel containing a body. The series, then, does not run from tent to pole; it begins at the pole. Strike the tent from the reckoning and what Rabbi Akiva has produced is four, not five. Behind this lies a wider principle: whatever is found within the tent is regarded as if it were in direct contact with the corpse.
A different approach in the Bartenura
The Bartenura advances another chiddush here, which we will mention rather than pursue. In his view the pole need not have stood within the tent at all; it may have been in contact with the tent from without, and even so it does not descend a level. On this reading, had the pole in fact been standing inside, not even Rabbi Akiva would have reckoned tent and pole as two distinct stages, for whatever is under the ohel forms a single unit. Rabbi Akiva's tally of tent first and pole second works only because the pole was in contact with the tent from outside it. Then the tent is stage one, the pole in contact with it is stage two, the man who lays hold of the pole is stage three, the keilim he handles are stage four, and the adam or keilim that come up against those keilim are stage five.
What still needs explaining on this approach is the ground of the Chachamim's objection: why would they regard even a pole in contact with the tent from without as if it were the tent itself? Their view is that the entire ohel carries the status of the corpse, with nothing dividing the body from the covering above it. A pole in contact with such a tent is not in contact with something that absorbed tumah from the corpse; it is as though it is in contact with the corpse itself. This principle deserves further discussion, and we will take it up later on, be'ezras Hashem.