One of the many types of sanctified animals is a bekhor – a firstborn animal from kosher species – that must be given to akohen. The kohen is obligated to bring the bekhor to the Temple in Jerusalem to be sacrificed, and he gets to eat its meat. In the event that such an animal develops a mum – a blemish that precludes it from being brought as a sacrifice – in contrast with other sanctified animals it is not redeemed and exchanged, rather it becomes the property of the kohen who can slaughter it and eat it even outside the Temple. Thus, unlike other kodashim that do not operate in the absence of a Temple, the laws of bekhor apply even today, and in theory a firstborn animal must be set aside to be given to a kohenwho can make use of it after it develops a mum. (Due to concern with the possibility that the bekhor may be misused, the recommended practice is to arrange for the animal to be sold, at least in part, to a non-Jew so that the laws of bekhorshould not apply.)
The Mishnah on yesterday’s daf (=page) discusses the ramifications of an animal that encounters difficulty while delivering an animal that will be a bekhor. Since the holiness of the bekhor is dependent on its playing the role of a petter rehem – it must “open the womb” (see Shemot 13:2, 12) – only if the majority of the animal has breached its mother’s womb will it become sanctified. Only in such a case will the firstborn be treated with the sanctity of a bekhor; if only parts of the fetus emerge it has no sanctity so the owner is free to kill it in order to save the mother and throw its meat to the dogs.
- What if a weasel inserted its head into the womb and took the fetus into its mouth and extracted it, and then inserted its head again into the womb and spit it out, and then the fetus came forth of its own?
- What is the law if one joined the wombs of two animals to each other and the fetus issued from one womb and entered the other? Do we say that it exempts only its own mother from the law of bekhor but it does not exempt the other animal or perhaps it exempts also another animal?
Tosafot point out that these cases are impossible and will never happen, but they are raised in the course of discussion for reasons of derosh ve-kabel sakhar – “discuss and receive reward” for engaging in Torah study. It should be noted that it is not unusual for the Gemara to raise theoretical questions such as these in order to examine foundational questions and extract rules that may have practical applications. Modern medicine has given Rava’s theoretical questions true relevance, for example regarding questions of surrogate motherhood.