In a mishnah back on Zevachim 70, we learned that when an animal from which we are prohibited from deriving benefit gets mixed into a group of animals that are designated to be sacrificed, none of the animals may be used for any purpose and all must die. This is true even if the ratio of prohibited animals to permitted ones is one to ten thousand — a ratio the rabbis often use as a stand-in for infinity. This tells us that no matter how big the flock, one prohibited animal disqualifies it in its entirety.
On today’s daf, we encounter a suggestion for how such a group of animals could be sacrificed as their owners intended:
Let us draw out and sacrifice one from (the mixture), and say: Any item that separates is separated from the majority.
There is a principle in Jewish law that when a single item of uncertain status is removed from a mixture, we can assume its status is like the majority of the mixture. For example, if a person finds a piece of meat in the public square, if a majority of the local butcher shops are kosher, we consider the meat to be kosher. If the majority of butcher shops are not kosher, we consider the meat to be unkosher. Applied to our case, we can therefore assume that if we select an animal from a group of designated animals that has been infiltrated by a single prohibited animal, the animal is a permitted one since the majority of the group is permitted. This makes sense, but it’s not in line with the mishnah. So the Gemara tries to square the circle.
(This is the removal of an item from its) fixed place, and anything fixed is considered half and half.
The Gemara suggests that there is another principle at play in the mishnah, namely that if a prohibited animal gets mixed up in a group of permitted animals, we assume that each animal is equally likely to be permitted or prohibited as long as the animals are stationary. Mathematically, of course, this is absurd. Just because the animals are fixed in place does not magically create a situation where each animal has a 50 percent likelihood of being the prohibited one, but that is how the rabbis see it.
If we assume then that the mishnah is dealing with a case where the animals are standing still, we have resolved to contradiction. But in doing so, we have practically reduced the number of cases in which all of the animals become prohibited to zero, as all we have to do is get the animals to move around a bit (or wait until they do so on their own) and they’ll lose their fixed-place status. As soon as that happens, the majority principle will apply and the intended sacrifices can resume.
Rava suggests that this is precisely why the mishnah prohibits all the animals, as it is concerned that as soon as they all start moving around, multiple priests will show up to select an animal for slaughter, and if enough of them do, a majority of animals would be removed. This would shift our assumption that the prohibited animal remains in the pen and those that have been selected will have been prohibited. To save everyone the trouble, the mishnah forbids the sacrifice of all the animals from the start.
The Gemara challenges this explanation based upon the assumption that it’s not possible for a group of priests to select animals all at once. It makes much more sense that they would do so one at a time. This would ensure that the selected animal is from the permitted majority until only two animals remain. This in turn leads the Gemara to suggest that Rava really suggested something else — namely, that the rule in the mishnah forbids people from selecting an animal from a mixed flock when it is in motion because it is concerned this will lead people to select an animal from a fixed flock, which is prohibited on the basis of the 50-percent rule we learned above. In other words, the mishnah chooses to forbid what is technically permitted (taking a moving animal) to prevent something that is forbidden (taking a fixed animal).
In its attempt to make sense of what this mishnah is teaching, the Gemara leads us on a long and winding path. Yet, the mishnah’s main concern seems far more simple: To prevent a prohibited animal from being offered as a sacrifice, it prohibits the entire flock into which the prohibited animal has been absorbed. No further explanation required.
Read all of Zevachim 73 on Sefaria.
This piece originally appeared in a My Jewish Learning Daf Yomi email newsletter sent on November 26, 2025. If you are interested in receiving the newsletter, sign up here.
