Ohalos, Chapter 7, Mishnah 5. Our chapter has been dealing with the tumah that comes into a house when a baby is born without a neshama, and with the status of the mother and of whatever else is under that roof. Our mishnah takes up a case that adds a whole new question: a woman gives birth to twins, and one of the two comes out without life. What is the din of the other one?
The first case: "yotzo harishon meis v'hasheini chai, tohor." The first of the twins was born lifeless, and it was carried out of the house immediately, before its brother emerged. Then the second twin was born, alive, baruch Hashem. The mishnah rules that this second baby is tohor. The reason is straightforward: as long as the second baby was still inside its mother, it could not contract tumah, even though its twin had already been born and was already a source of tumah. Whatever was going on inside the mother is simply not our problem. Once the lifeless twin had been removed from the house before the living one entered the world, there is nothing to make the living one tomei.
The second case is the mirror image: "harishon chai v'hasheini meis, tomei." Here the twin with life emerged first, and only afterward came the twin that had no life in it. The mishnah rules that the firstborn, the living child, is tomei. And that ruling holds even where the living child had already been carried outside the dwelling before the second twin emerged.
Why should this be so? If the living infant was already outdoors, what could possibly have conveyed tumah to it? The mefarshim propose several answers, and I want to present the most straightforward one. When a living child exits and the lifeless child follows immediately on its heels, the odds are strong that the two came into contact at the moment of birth, and it is that contact which renders the living child tomei.
But wait a moment. If that logic is so compelling, why not apply it to the first case as well? There too the twins came out one after the other. Why not assume that the living baby, coming out second, touched the lifeless baby that had come out first?
Here we come to something interesting. The mefarshim explain that there is a real difference in how the two of them emerge. A living baby is in no hurry to be born. It stays where it is until it has no choice at all, and only then does it come out. A baby without a neshama simply rolls out.
Al pi drush one can say it beautifully. The living child stands under the rule of "al korchacha atah chai," it is brought into this world against its will. Why would it wish to leave where it is? There it sits and learns with the malach; azoy steht, it learns kol haTorah kulah. The child with no neshama has already sent its neshama up to Shomayim, and its body simply rolls out. So much for the drush. But in terms of derech hateva the identical picture emerges as plain metzius: a living infant does not exit quickly, while an infant without life exits with ease.
Now let us work out the cheshbon with this in hand. In the earlier case the child without life exited first, quickly and effortlessly, while the living twin that followed was in no rush at all. A genuine gap separated the two, so we do not presume that they touched, and the living twin stays tohor. The second case is precisely the opposite. The living child came first, which means it lingered and was slow in emerging, and while it was still on its way the lifeless twin came tumbling out right behind it. There the likelihood of contact between them is considerably greater, and therefore the living child is tomei.
"Rabbi Meir omer": Rabbi Meir holds that the answer varies from case to case, and he sets the dividing line somewhere else entirely. An infant is born inside a sac, a shafir. With twins, the two are sometimes carried together in one sac and sometimes each in a sac of its own. Rabbi Meir therefore asks us to determine which sort of twins we are dealing with.
"Bishfir echad, tomei." Where both shared a single shafir, the living twin is tomei, since the two emerged as one, and we must reckon seriously with the strong likelihood that the lifeless twin made contact with its brother once the two had left the mother, at that stage which halachah calls being born.
"Bishnei shefiros, tohor." If each twin had its own sac, the living one is tohor, and according to Rabbi Meir this holds even where the living baby was born first. Two separate sacs mean that they came out one and then the other, with enough of a separation between them that we need not assume contact, even granting that the lifeless twin came out more quickly than its brother.
Let us review the mishnah from the beginning. Where the child without life emerged first and the living child second, the living child is tohor, since we do not presume that it made contact with its lifeless twin once that twin was outside. Whatever transpired within the mother is of no halachic concern to us at all; our discussion begins at the moment of emergence and moves forward from there. And obviously the mishnah is speaking of a case where the lifeless infant had already been taken out of the dwelling before its brother was born. But where the living child preceded and the one without life followed, the living child is tomei, for the reason we explained: a living infant emerges slowly while one without life slips out easily, so it stands to reason that the latter touched the former while the former was still holding back. And Rabbi Meir maintains that it varies: with one shared shafir the living child is tomei, because we assume they touched at the stage when they were already being born; but with two separate shefiros, even where the living child emerged first, Rabbi Meir rules that it stays tohor.