Ohalos, Chapter 11, Mishnah 7. This mishnah presents one of the most vivid cases in the entire maseches: a dog swallowed a piece of basar hameis, flesh of a corpse, and then died while lying across the threshold of a house, half in and half out. Is the house tamei? Four Tannaim look at that dog and each one measures something different.
First, a Principle: Tumah Inside a Living Creature
Before we open the mishnah's case, we need a rule that the mishnah takes for granted. As long as the dog is alive, it makes no difference at all where it stands. It could walk fully into the middle of the house with that basar hameis sitting in its stomach, and the house would remain tahor. This is the principle of tumah beluah beba'alei chayim, tumah that has been swallowed into a living creature. Such tumah is simply not metamei anything. And this is not limited to a dog. Tumah swallowed by a person or by a beheimah behaves the same way: while that person or animal is alive, the swallowed tumah is inert and conveys nothing.
Our mishnah, however, deals with the moment after the dog dies. Now the swallowed basar hameis is once again a live halachic problem, and the dog's carcass happens to be lying in the worst possible place.
The Case
"Kelev she'achal basar hameis," a dog consumed flesh from a corpse, "umeis hakelev," and afterward the dog itself died, "umutal al ha'iskufah," and its body now lies stretched across the doorstep. Visualize the position carefully: the belly, which contains the basar hameis, rests outside; the neck and head reach into the dwelling. Our question is whether the tumah sitting in that belly manages to penetrate the dwelling.
Rebbe Meir: Measure the Neck
Rebbe Meir says it depends entirely on the thickness of the dog's neck. "Im yeish betzavaro poseiach tefach, meivi es hatumah": if the neck has an opening of a tefach, it brings the tumah into the house. "Ve'im lav, eino meivi es hatumah": and if not, it does not.
How would we know whether a neck has a tefach of width? Take a string and run it around the neck. If the circumference measures three tefachim, that is a reliable siman that the width across is a tefach, based on the standard rule: "kol sheyeish berochbo tefach, yeish behekeifo shelosha tefachim," whatever has a tefach across its width has three tefachim around its circumference.
And what does a tefach of width accomplish? Once the passage through the neck is a tefach wide, the upper part of the dog forms an ohel over the tumah beneath it. That ohel carries the tumah forward from the stomach, through the neck, and joins with the ohel of the house itself. Without a tefach, there is no ohel to carry anything, and the house stays clean.
Rebbe Yosi: Even Without a Tefach, Look Straight Up
Rebbe Yosi says the matter is not so quickly settled. Even if the neck lacks a poseiach tefach, we are not yet finished; some careful measuring is still called for. "Ro'in es hatumah": we look at where exactly the tumah is lying, namely at the spot in the dog's stomach that holds the basar hameis, and we measure straight upward from there, as if dropping a plumb line or shining a laser beam vertically.
Why straight up? Because without an ohel we are dealing with tumah retzutza, tumah that is pressed in place with no covering to spread it sideways. Such tumah rises in a direct vertical column. So the only question is where that column lands. "Mikeneged hamashkof ulifnim, habayis tamei": the mashkof is the lintel, the top of the doorframe against which the door closes. If the tumah, measured upward, falls at the line of the lintel or inward from it, then it has entered the airspace of the house and the tumah spreads through the whole house. "Mikeneged hamashkof velachutz, habayis tahor": if the vertical line from the stomach would land outside the doorway, missing it, the house is tahor.
Note the assumption running underneath this: the mishnah takes it as given that a dog's stomach never contains a space of a tefach by a tefach, so the stomach itself is never an ohel. The only place where an ohel could possibly form is the neck, and in Rebbe Yosi's case we have already stipulated that the neck is too narrow. Hence the tumah rises vertically, and everything depends on whether that rising column passes inside the doorway or outside it.
Rebbe Eliezer: Which Way Is the Dog Facing?
Rebbe Eliezer approaches the scene from a completely different direction. "Piv lifnim, habayis tahor": should the dog's mouth be turned toward the interior, so that its other opening, at the rear, points out toward the street, the dwelling remains tahor. "Piv lachutz, habayis tamei": but reverse the position, with the mouth pointing outside and the rear opening facing in, and the dwelling contracts tumah.
His reasoning: "shehatumah yotzeis derech shulav," the tumah is destined to exit through the animal's lower opening. Rebbe Eliezer is speaking about the same set of facts, a neck that is not a tefach wide and a stomach positioned outside the house, and he nevertheless says that the deciding factor is the direction in which the tumah was headed. From the moment the dog swallowed that meat, its natural course was to emerge from the rear. Therefore the halachic address of the tumah follows that exit point. Mouth inside and rear outside means the tumah is on its way out of the house, so the house is tahor. Mouth outside and rear inside means the tumah is on its way into the house, so the house is tamei.
Rebbe Meir and Rebbe Yosi do not accept this line of thinking at all. Their objection is that the exit route only functions while the dog is alive, and once the dog is dead nothing is going to come out of it anywhere. So the two halves of Rebbe Eliezer's argument never coincide: while the dog lived and food was actually moving through it, there was no tumah at all, since tumah beluah in a living creature is not metamei; and now that there is tumah, the digestive process has stopped. That is the classic response of "man d'shafach," the two conditions never overlap, so the future exit point cannot be the deciding factor.
Rebbe Yehuda ben Beseira: Either Way, Tamei
"Rebbe Yehuda ben Beseira omeir: bein kach uvein kach tamei," whether it is this way or that way, the house is tamei. The Bartenura explains that his words sweep away every one of the distinctions we have just learned:
- Whether the mouth faces inward or outward.
- Whether the tumah, measured straight upward from the stomach, would fall inside the doorway or outside it.
- Whether the neck has a width of a tefach or does not.
In every one of these situations the house is tamei. Rebbe Yehuda ben Beseira agrees with the underlying approach that we judge the tumah by where it is destined to emerge, but he says the destination is not fixed in one direction. The swallowed meat may come out the back through the normal digestive route, and it may just as easily come out the front, since a dog frequently vomits up what it has eaten. Since the tumah has an exit at both ends, it makes no difference which end is turned toward the house. Either way, the tumah is considered to be reaching in, and the house is tamei.
How Long Before the Meat No Longer Counts?
The mishnah proceeds to the natural next question: "kama sisha bemei'av," what span of time must the basar hameis sit inside the animal before we declare it fully broken down and no longer capable of conveying tumah at all? Once that span has elapsed, the entire case we have been analyzing evaporates, because nothing of the flesh was left when the animal expired.
Where a dog is concerned, the measure is "shelosha yamim mei'eis le'eis," three days reckoned from one point in time to the identical point, meaning three complete cycles of twenty-four hours. Suppose the animal swallowed the piece on Monday morning at nine: we count to Tuesday at nine, Wednesday at nine, and Thursday at nine. If the dog expires only once Thursday at nine has passed, there is no question of tumah at all, for the flesh has already been broken down and is gone.
The Bartenura cites a lovely teaching found in the Gemara in Maseches Shabbos explaining why a dog's digestion moves so slowly. "Galui veyadua," it is revealed and known before the Ribono Shel Olam that a dog's rations come to it sparingly; this creature does not easily manage to secure the food it requires. Therefore the Ribono Shel Olam arranged ("mash'ha achilaso") that whatever it eats should linger within it for three days, keeping it satisfied and sparing it the pain of hunger. "Verachamav al kol ma'asav," His mercy rests upon everything He has made. The very construction of this animal's innards is an expression of Divine kindness, designed so that it should not suffer. And that same unhurried digestion is exactly what produces our three day measure: once the three days have elapsed, nothing of the flesh survives and there is no tumah left to discuss.
Birds and Fish
"Uve'ofos uvedagim," but with birds and fish that swallowed basar hameis, the shiur is far shorter: "kedei shetipol la'eish vetisareif," the amount of time it would take for the meat to be dropped into a fire and burned up. In other words, practically immediately; as soon as such a creature has eaten the meat, we regard it as digested. "Divrei Rebbe Shimon," this is the opinion of Rebbe Shimon.
"Rebbe Yehuda ben Beseira omeir: be'ofos uvedagim mei'eis le'eis." Rebbe Yehuda ben Beseira maintains that where fowl and fish are concerned, one must wait a full mei'eis le'eis, an entire twenty-four hour period.
To Review
A dog swallowed basar hameis, died, and is lying on the threshold with its stomach outside the house and its head and neck inside. While it was alive nothing would have been tamei, since swallowed tumah in a living creature conveys nothing. Now that it is dead: Rebbe Meir measures the neck, and a poseiach tefach creates an ohel that carries the tumah in and joins the ohel of the house. Rebbe Yosi says that even without a tefach we drop a vertical line from the tumah in the stomach: land at the lintel or inward and the house is tamei, land outside the doorway and the house is tahor. Rebbe Eliezer judges by the direction the dog is facing, since the tumah was destined to exit from the rear: mouth inward, tahor; mouth outward, tamei. Rebbe Yehuda ben Beseira rules tamei in every one of these configurations, since the tumah may emerge from either end, front or back. And the whole discussion applies only within the digestive window: three full days for a dog, while for birds and fish it is immediate according to Rebbe Shimon and a full twenty-four hours according to Rebbe Yehuda ben Beseira.