Ohalos, Chapter 3, Mishnah 5. The Mishnah returns to a subject that was introduced earlier in the maseches and now asks for a precise definition: "eizehu dam tfusa?" What exactly is the blood of death that Chazal declared metamei b'ohel?
Reviewing the Background
Earlier in the maseches, in perek beis Mishnah beis, we were taught that a revi'is of dam tfusa brings about tumas ohel exactly as a revi'is of a meis's blood does. The two are not on equal footing, though. Where a full revi'is drained out of the body after the person's petirah, the tumah is mid'oraisa. Dam tfusa, where a portion of the blood left him while he yet lived and a portion left him once his neshamah had gone, is metamei only mid'rabbanan.
The word tfusa itself comes from a posuk in Yechezkel, "va'e'evor alayich va'erech misboseses b'damayich," which pictures someone wallowing about in her blood. In its own setting that posuk is describing the blood of a newborn infant, and it closes with the words "b'damayich chayi," by your blood you shall live, which Chazal expound as an allusion to the blood of the korban Pesach and the blood of milah. Even so, the wording of that posuk lends its name to the blood pooled around a person as he dies.
The Opinion of Rabi Akiva
Now come the particulars. The Mishnah's case is "shminis b'chayav u'shminis b'moso." A shminis equals one eighth of a log, and since a revi'is halog comes to roughly three to five ounces, a shminis works out to exactly half a revi'is. Picture, then, half a revi'is draining from the person during his lifetime and another half draining from him after he died, the two blending together into one complete revi'is. Such a revi'is, teaches the Mishnah, qualifies as dam tfusa and is metamei mid'rabbanan. So holds Rabi Akiva.
Look closely at how far Rabi Akiva is willing to go. Plainly there is no whole revi'is here that drained out after death, since some of what lies before us left the body during the man's lifetime. Yet because a complete revi'is is now sitting in front of us, Rabi Akiva labels it dam tfusa that is metamei b'ohel. He does insist on a floor, however: no less than half the quantity, a whole shminis, has to have drained out after the petirah. Should the amount that left him during his lifetime exceed a shminis, we are no longer dealing with dam tfusa.
The Opinion of Rabi Yishmael
Rabi Yishmael takes issue with this. To his mind, unless a whole revi'is drained out after death there is nothing here to call dam tfusa. What situation, then, does he describe? One entire revi'is left the man b'chayav, in his lifetime, and a second entire revi'is left him b'moso, after his death. "V'nitla mizeh umizeh revi'is": the two revi'iyos intermingled, and out of that blend a revi'is was drawn off. That, in Rabi Yishmael's view, is what dam tfusa means.
The Opinion of Rabi Elozar b'Rabi Yehuda
Rabi Elozar b'Rabi Yehuda throws out both of the earlier cases: "zeh v'zeh k'mayim," the two of them amount to nothing more than water. Neither is metamei, because in neither instance is there a whole revi'is that originated from a meis.
So what does count as dam tfusa in his opinion? A tzaluv, someone hanged, "shedomo shoses," whose blood gushes out in a stream, and a revi'is of blood is discovered on the ground below him. Such blood is tamei, for two reasons. First, it is entirely conceivable that the whole revi'is drained out l'achar misah. Second, even should that not be so, we know beyond doubt that some blood which left the body after death is mixed into what is lying there, if only a single drop.
Put differently, Rabi Elozar b'Rabi Yehuda demands two things before the rabbinic takanah of dam tfusa takes effect. One, it must be genuinely conceivable that all of the revi'is drained out after death. Two, we must be sure beyond doubt that a minimum of one drop within it left the body after death. When you look for a case in which both of these hold true, the only one you find is the tzaluv whose blood gushes down.
Why Only a Tzaluv
The Mishnah draws the contrast openly: "aval hameis," a regular meis resting on the floor or in a bed, whose blood typically behaves as "shedomo menateif," trickling out one drop after another instead of gushing in a stream, if a revi'is of blood is discovered underneath him, it is tahor.
At first glance this is puzzling. Here too there is surely a drop of blood that emerged after death, and here too it is possible that a full revi'is emerged after death, so both of the conditions would seem to be met. The answer lies in the manner in which the blood came out. It may well be that the blood which came out during his lifetime landed first and formed a pool on the ground. Every subsequent drop, including the drops that left the body after his petirah, falls one at a time into that existing pool and is batel in it. Halachically, once a drop is nullified it is treated as though it does not exist, so we are left without any blood that came out after death. Had the blood come streaming down all at once, there would be no bittul; but drop after drop, bittul takes effect.
Rabi Yehuda Reverses the Ruling
Rabi Yehuda holds the exact opposite on both counts. "Hashoses," where the blood poured out because the person was hanging, is tahor. Why? Because we have no way of knowing that the blood which emerged after death actually reached the ground. Quite possibly it remained on the tree from which he was hanging, and the blood found below contains nothing that left the body after death.
"Hamenateif," however, where the meis is lying on a bed and the blood drips down, is tamei, since everything that left the body landed right there on the floor. And the argument of bittul does not trouble Rabi Yehuda at all, because he maintains ein dam mevatel dam: blood is never nullified in blood.
This is not a stance Rabi Yehuda confines to blood. We meet it in Maseches Zevachim and in other places too: his principle is min b'mino eino batel, that nothing is ever nullified inside its own species. Milk spilled into chicken soup is capable of becoming batel; milk spilled into milk is not.
The Ran's Explanation
Rabi Yehuda's reasoning is laid out by the Ran in Nedarim. Nullification, he explains, needs a tzad hamisnaged, some opposing element. Imagine a basin filled with blue paint, and with a dropper you add to it one further drop of blue paint. Would anyone suggest that the drop you added has ceased to exist? Certainly not: weigh the basin's contents carefully and that additional drop is entirely accounted for. Now let one drop of white paint fall into that same basin of blue. For every practical purpose the white is finished; search as you like and no white paint will turn up. Since bittul requires something to stand against, min b'mino, in Rabi Yehuda's view, is never nullified.
Summary
Mid'oraisa, blood of a meis is metamei only when a full revi'is emerged after death. Dam tfusa, blood of which some emerged before death and some after, is metamei only mid'rabbanan, and the Mishnah records three views as to what qualifies:
- Rabi Akiva: a shminis (half a revi'is) came out during his lifetime and a shminis came out after his petirah; together they form a revi'is, and that is dam tfusa which is metamei mid'rabbanan.
- Rabi Yishmael: without a full revi'is that emerged after death there is no dam tfusa. His case is a full revi'is from his lifetime and a full revi'is from after his petirah that became mixed together, from which a revi'is was then taken.
- Rabi Elozar b'Rabi Yehuda: both of those cases are like water and are tahor. He requires two conditions: that it be possible that an entire revi'is emerged after death, and that we know for certain that at least one drop in the revi'is emerged after death. That combination exists only by a tzaluv, where the blood pours down. By an ordinary meis the blood drips, and every drop falling into the pool of blood that emerged during his lifetime is batel, leaving us halachically with no blood from after death.
Rabi Yehuda turns the whole halachah around. By a tzaluv he rules tahor, on the possibility that whatever blood left the body after death stayed behind on the tree and never made it to the ground at all. Where the meis is not hanging, by contrast, every bit of blood that left him lies right there in front of us, and the bittul argument does not move him in the slightest, since his principle is that min b'mino is never nullified.