As we learned in the Mishnah (daf, or page 27a) it is not necessary to fully cut the esophagus and the trachea; it is sufficient to cut the majority of those simanim (or, in the case of a bird where only one is necessary, it is sufficient to cut the majority of one of those two simanim). The Gemara points out that when teaching this law, the Mishnah appears repetitive and redundant, since we find the same law in the opening line of the Mishnah and in the closing line of the Mishnah.
In response to this question, Rav Hosha’aya suggests that both are necessary – one to teach that this law is true in ordinary situations of ritual slaughter and the other to teach that this law is true specifically in kodashim, in ritual slaughter that is part of the sacrificial service in the Temple. He explains that we need to be taught this law in both circumstances:
- Had the Mishnah only taught this law in the context of ordinary ritual slaughter, we might have thought that it is only true in settings where the point is to perform shehitah on the animal. In the case of kodashim, however, where the slaughter is needed for the blood of the sacrifice, perhaps we need the simanim to be entirely cut.
- And had the Mishnah only taught this law in the context of the sacrificial service, we might have thought that only there we need the majority of the simanim to be cut. In the case of ordinary slaughter, however, perhaps cutting half of the simanim would suffice.
The Mishnah therefore must teach us the law in both cases.
As we have learned in Masechet Zevahim (see, for example, daf 25 ), the service of collecting the blood of the offering and sprinkling it on the altar is the centerpiece of the sacrificial service. Once that is performed, atonement has been accomplished even if the other parts of the service are not done. Although the esophagus and the trachea do not, themselves, carry blood, it is possible that if they are not cut completely, the nearby blood vessels may not be cut, either.