The Gemara discusses the prohibition of consuming non-Jewish milk, known as halav akum. The initial concern raised is that a non-Jew might mix non-kosher milk with kosher milk. However, this concern is dismissed because the colors are distinct: kosher milk is white, while non-kosher milk is greenish or yellowish, making any adulteration immediately noticeable. Even if the non-kosher milk were mixed, the Gemara explains that non-kosher milk does not congeal to form cheese. Therefore, if one were buying milk for cheesemaking, the failure to congeal would immediately reveal the presence of non-kosher milk.
The Gemara then considers a scenario where one buys milk not for cheese, but for yogurt or other purposes where congealing is not a factor. In such a case, the advantage of the cheese test is lost. The Gemara suggests that one could take a small amount of the milk and test it for cheese. If it congeals, it is kosher. However, this solution is also challenged. When cheese is made from kosher milk, a remnant called whey (kamcha) is left over. The concern is that if non-kosher milk was present, it would not congeal but would rise to the top and be strained out along with the whey. This means the remaining whey might still contain non-kosher elements, rendering the entire batch problematic. Thus, even testing for cheese would not guarantee the purity of the whey. This leads to the conclusion that according to this reasoning, one cannot rely on the cheese test to permit halav akum, even for cheesemaking, because of the lingering concern about the whey.
Next, the Gemara addresses the prohibition of non-Jewish bread, known as pat akum, as stated in the Mishnah. Rabbi Hanan states that the rabbinic court (Beit Din) never permitted pat akum. This implies that if it was ever permitted, it was based on a misunderstanding. The Gemara recounts a story where Rabbeinu HaKadosh was in a field and was served non-Jewish bread. He remarked on its quality, questioning why the Sages prohibited it. The Gemara explains that the prohibition on pat akum stems from a concern that eating it could lead to intermarriage. Rabbeinu HaKadosh questioned why this concern should apply in a field, where social interaction leading to marriage is less likely than in a city.
This statement of Rabbeinu HaKadosh was misinterpreted by some as a blanket permission for pat akum, at least in fields. However, the Gemara clarifies that he was merely questioning the scope of the prohibition, not issuing a permit. The Beit Din of Rabbeinu HaKadosh never formally permitted pat akum. A second version of the story is presented by Rav Yosef and Rav Shmuel bar Yehuda. In this version, Rabbeinu HaKadosh was seeking bread for his students and asked if there was no bakery available. Some understood him to be lenient regarding bread from a non-Jewish bakery (paltar) if no Jewish bakery was available. However, the Gemara clarifies that he was merely inquiring if there was no Jewish bakery nearby, not permitting non-Jewish bread.
Rav Helbo further clarifies that even according to the understanding that Rabbeinu HaKadosh was lenient regarding a non-Jewish bakery, this leniency would only apply if there was no Jewish bakery available. If a Jewish bakery (paltar Yisrael) was present, pat akum would remain prohibited. Rabbi Yohanan offers another perspective, stating that even if a non-Jewish bakery is permitted in a field, it would still be prohibited in a city due to the concern of intermarriage.
The Gemara then delves into the core question: if all these instances of permitting pat akum were based on misunderstandings, where do the actual leniencies come from? The commentators (mefarshim) discuss this. One interpretation of Rabbi Yohanan’s statement is that he adds a stringency, asserting that even the leniency of Rav Helbo (permitting pat paltar akum when no paltar Yisrael is available) applies only in a field, not in a city. Another interpretation is that Rabbi Yohanan adds a leniency, permitting pat paltar akum even where pat Yisrael is available, but only in a field. A third understanding suggests that Rabbi Yohanan and Rav Helbo are not in disagreement, but each holds specific leniencies and stringencies based on different factors, such as the availability of Jewish bread or the location (city vs. field).
Ultimately, the Gemara concludes that the leniency for pat akum, which is widely practiced today, stems from the fact that the prohibition was difficult for the majority of the community (tzibur) to uphold. A rabbinic decree (gezera) that is not accepted by the majority and cannot be upheld by them can be nullified by a later Beit Din, even if the later Beit Din is not greater in wisdom or number than the original one. This is because a decree needs to be accepted and practical for the community to be binding. The story of Rabbeinu HaKadosh’s questioning is understood as a reflection of this difficulty, and the subsequent analysis by the Sages indicates that they allowed the practice to continue, effectively nullifying the original prohibition due to its non-acceptance.
The Gemara then turns to the prohibition of non-Jewish oil (shemen akum). Rav attributes this prohibition to a decree made by Daniel, again due to the concern of intermarriage. Shmuel, however, offers a different reason: the oil becomes non-kosher due to contact with non-kosher residue (peletah) from non-Jewish pots, which are considered non-kosher. The Gemara initially challenges Shmuel's reasoning, asking who is so stringent about such contact. The discussion clarifies that olive oil, being sharp, can extract forbidden substances from the walls of a non-kosher pot, even if the pot is cold, thus rendering the oil forbidden.
This leads to a fundamental dispute between Rav and Shmuel: is the prohibition of shemen akum a decree against intermarriage (Rav) or a concern about non-kosher extractions from pots (Shmuel)? Bar Shmuel Bar Marta presents a testimony from Rabbi Simlai, who stated that the Beit Din of Rebbe Yehuda HaNasi voted to permit shemen akum. This is possible according to Shmuel’s reasoning: if the non-Jewish pot has not been used for 24 hours, the non-kosher residue becomes "spoiled" (pagum) and does not render the oil forbidden. Since this is a matter of logical reasoning, not an enactment (takana), a later Beit Din can disagree with the earlier reasoning without needing to be greater in wisdom or number.
However, if Rav’s view is accepted—that the prohibition is a decree by Daniel against intermarriage—then Rebbe Yehuda HaNasi’s Beit Din could not have nullified it. A decree by a previous Beit Din can only be overturned by a later Beit Din that is greater in both wisdom and number. Daniel was certainly greater than Rebbe Yehuda HaNasi. Shmuel’s student sharply challenges the testimony of Rabbi Simlai, questioning his trustworthiness, as he was from Lod, a place known for laxity in such matters. This highlights the gravity of overturning established decrees.
Rav then provides scriptural support for his view, citing the verse where Daniel resolved not to defile himself with the king's food and drink. Rav interprets "drinks" to include oil, suggesting that Daniel’s personal resolve became a public decree. Shmuel counters by citing a teaching that the prohibition of non-Jewish oil, wine, and daughters was among the eighteen decrees made by Beit Shammai. This contradicts Rav’s claim that Daniel made the decree. The Gemara reconciles these views by suggesting that Daniel initially made the decree for the city (due to intermarriage concerns), and Beit Shammai later expanded it to include fields. The city decree, being from Daniel, would be unbreakable, while the field decree, from Beit Shammai, might be subject to the principle of non-acceptance by the community.
The question then arises: how could Rebbe Yehuda HaNasi nullify the decree on oil, given the ironclad nature of Beit Shammai’s eighteen decrees, which are generally considered unbreakable even by a prophet? Rav Mesharsheya explains that the reason Beit Shammai’s decrees are unbreakable is because they were widely accepted (pashat) by all of Israel. However, he clarifies that the decree on oil never truly caught on. A decree is only binding if it is both publicized and accepted by the majority of the community. Since the oil decree was not widely accepted and was difficult for the community to uphold, even a smaller Beit Din like that of Rebbe Yehuda HaNasi could nullify it. This principle is derived from a verse in the Torah, implying that a curse for violating a decree only applies if the decree was accepted by the entire nation.
In summary, a rabbinic decree requires two conditions to be unbreakable: widespread acceptance (pashat) and practicality for the community to uphold. If both conditions are met, no subsequent Beit Din, however great, can nullify it. If only one condition is met, a greater Beit Din might be able to nullify it. The prohibition of oil, however, met neither condition—it was not widely accepted, nor was it practical for the community. Therefore, even a smaller Beit Din could nullify it. This explains the current leniency regarding shemen akum. Rav himself eventually retracted his strict stance, accepting the testimony that Rebbe Yehuda HaNasi had nullified the decree, and subsequently permitted shemen akum.
The Gemara then lists the eighteen decrees made by Beit Shammai, which include non-Jewish bread, oil, wine, and daughters. The prohibition concerning non-Jewish daughters (benotahen) is clarified. It is not about the Torah prohibition of intermarriage with the seven nations of Canaan, but rather a decree that non-Jewish baby girls are considered ritually impure (nida) from birth. This is to discourage intimacy, preventing intermarriage or illicit relations. Some say the primary concern is to prevent closeness that could lead to idolatry.
The discussion then traces the evolution of prohibitions against illicit relations with non-Jewish women. The Torah prohibits marriage with the seven nations. Beit Shammai extended this prohibition to all non-Jewish women. Furthermore, while the Torah prohibits marriage, it does not explicitly prohibit casual illicit relations (derech znut) with non-Jewish women. However, the Gemara clarifies that even such relations were prohibited by the Beit Din of Shem and Ever, as evidenced by the story of Yehuda and Tamar. The primary concern in the Torah was a non-Jewish man with a Jewish woman, as he might draw her to idolatry. The reverse—a Jewish man with a non-Jewish woman—was not explicitly prohibited by the Torah, as she was not seen as capable of drawing him away. Beit Shammai extended the prohibition to a Jewish man with a non-Jewish woman.
The Gemara further refines this, stating that the Torah only prohibited public illicit relations with a non-Jewish woman (as in the case of Zimri and Kozbi). The Beit Din of the Hasmoneans extended this to private relations. They imposed four distinct prohibitions (nashgah or nashgaz) on a Jewish man who engages in relations with a non-Jewish woman: she is considered a nida (even though her blood is not ritually impure by Torah law), a maidservant (shifha), a married non-Jewish woman (goyah eshet ish), and a harlot (zonah) if the man is a Kohen. These decrees were made to prevent a Jewish man from becoming accustomed to forbidden relations, which could then lead him to violate similar prohibitions with Jewish women.
The Gemara then clarifies what Beit Shammai added to these existing prohibitions. While the Beit Din of the Hasmoneans prohibited relations (bi'ah), they did not prohibit seclusion (yichud) with non-Jewish women. Beit Shammai extended the decree to prohibit seclusion with non-Jewish women. This is distinct from the Torah prohibition of seclusion with forbidden relatives (arayot), and King David’s decree prohibiting seclusion with unmarried Jewish women (penuyot). Thus, Beit Shammai’s unique contribution was to prohibit seclusion with non-Jewish women.
Finally, the Gemara discusses another decree: non-Jewish baby boys are considered ritually impure like a zav (one with a seminal discharge). This was decreed to prevent Jewish boys from playing with them, out of concern that it could lead to homosexual acts (mishkav zachar). The age at which this impurity begins is debated. Initially, it is stated as one day old, but this is challenged as irrelevant to the concern of mishkav zachar, which only becomes relevant at age nine. The Gemara concludes that the impurity for boys begins at nine years and one day. Similarly, for non-Jewish girls, the impurity of nida begins at three years and one day, the age at which they are considered capable of relations, even though they may not yet be capable of seduction. This demonstrates the Sages’ proactive approach in enacting decrees to safeguard against potential transgressions.