A recent mishnah listed items of gentiles that are prohibited both to benefit from and to consume; the next introduced items that it’s forbidden to consume, but not to benefit from; and today’s mishnah introduces items that are permitted both consumption and benefit. For example:
Milk that was milked by a gentile and a Jew watched him.
While milk extracted without Jewish supervision is forbidden, as we fear the non-Jew may have mixed in milk from a non-kosher animal, if the act was supervised, we don’t say the milk is forbidden merely by virtue of the non-Jew’s involvement.The Gemara opens by comparing our mishnah to a beraita, which raises other potential relevant factors when considering the permissibility of non-Jewish milk:
A Jew may sit beside a gentile’s flock and the gentile milks his animals and brings the milk to the Jew, and he need not be concerned.
The Gemara then comments:
What are the circumstances of this case? If it is known that there is no non-kosher animal in the gentile’s flock, isn’t it obvious that the milk is permitted? And if there is a non-kosher animal in his flock, then why is the milk permitted?
The Gemara points out that if there are no non-kosher animals in a non-Jew’s flock, and the milk comes straight from the field, we don’t need observation. Conversely, if non-kosher animals are among the flock, why is it sufficient for the Jew to be sitting nearby, if they can’t see the milking as it happens?The Gemara clarifies:
Actually, this is referring to a case where there is a non-kosher animal in the flock, and when the Jew is standing he can see the gentile, but when he is sitting he cannot see the gentile. Lest you say: Since when the Jew is sitting, he cannot see the gentile, we should be concerned that perhaps the gentile will bring non-kosher milk and mix it with the kosher milk, the beraita therefore teaches us that since when the Jew is standing, he can see him, the gentile is fearful of being caught and does not mix anything into the milk.
It’s not a matter of whether the Jew is observing, but whether the non-Jew knows he might be watched. Presumably, just knowing he might be in a milking panopticon is enough to prevent trickery.
The Gemara’s logic of irtuti meirtat, “the non-Jew will be afraid,” is one premier 20th-century decisor Rav Moshe Feinstein invokes when he permits non-Jewish milk from factories. He notes that federal inspections of dairy plants function as regular checks on the nature of milk being produced. If a company is caught slipping camel’s milk into cow’s milk, they’ll be put out of business. These inspections, though only occurring several times a year, are frequent enough that we can assume the dairy plants would not feel comfortable attempting such a deception at any time in the year. Rav Moshe’s teshuvah is a foundational one for contemporary observant practice, though many Orthodox Jews, particularly to the right of Modern Orthodoxy, still only consume cholov yisrael — milk that has been watched by an observant Jew through the entire production process.
Read all of Avodah Zarah 39 on Sefaria.
This piece originally appeared in a My Jewish Learning Daf Yomi email newsletter sent on July 27, 2025. If you are interested in receiving the newsletter, sign up here.
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