One of the most well-known kosher laws is the prohibition of consuming meat and milk products together. While the story of how the rabbis came to forbid consumption of a beef and cheese hamburger has been told in detail,[1] a part of this tale is less known: How did the rabbis come to forbid consumption of a chicken and cheese burger?

The answer to this question begins in Deuteronomy 14:21, where, for the third time, the Torah commands:

לֹא תְבַשֵּׁל גְּדִי בַּחֲלֵב אִמּוֹ.

Do not cook a kid in its mother’s milk.[2]

While it was an important enough command to repeat – verbatim – three times in the Hebrew Bible, the precise meaning of this phrasing is unclear and was the subject of much debate in antiquity (and beyond).[3] In what follows, I discuss only some ancient Jewish interpretations of how this biblical prohibition was understood and put into practice in both the kitchen and at the table.

Philo’s Literal Interpretation: Don’t Be Cruel

In the Second Temple period, we have evidence that at least one Jew, the philosopher Philo of Alexandria, understood this biblical injunction literally, i.e., a prohibition to boil a baby animal in its own mother’s milk,[4] and saw in it a lesson in ethics. Philo argues that it is so easy to avoid eating the meat of a baby animal with milk that literally comes from the udder from which it nursed, that only cruel people with no sense of compassion would go out of their way to do this:

…it was grossly improper that the substance which fed the living animal should be used to season and flavour the same after its death, and that while nature provided for its conservation by creating the stream of milk and ordaining that it should pass through the mother’s breasts as through conduits, the license of man should rise to such a height as to misuse what had sustained its life to destroy also the body which remains in existence.

If indeed anyone thinks good to boil flesh in milk, let him do so without cruelty and keeping clear of impiety. Everywhere there are herds of cattle innumerable, which are milked everyday by cowherds, goat-herds and shepherds, whose chief source of income as cattle rearers is milk, sometimes liquid and sometimes condensed and coagulated into cheese; and since milk is so abundant, the person who boils the flesh of lambs or kids or any other young animal in their mother’s milk, shows himself cruelly brutal in character and gelded of compassion, that most vital of emotions and most nearly akin to the rational soul.[5]

According to Philo, if you were to cook meat from a baby animal in milk that comes from another mother, then that would not violate this taboo and would be “kosher.”[6] Philo could not have possibly meant to include fowl in this prohibition, since mother birds do not produce milk.

“All Meat Is Forbidden to Be Cooked with Milk”

The rabbis advance a very different interpretation. For them, the law is not specific, but general: all meat cannot be cooked with all milk. Further, the move from specific to general meant that they also consider this as a prohibition against eating—not just boiling—meat and milk together.[7] Hence, it regulates both kitchen practice and table practice. M. Hullin 8:1 states:

כל הבשר אסור לבשל בחלב חוץ מבשר דגים וחגבים.

All meat is forbidden to be cooked with milk, except for the meat of fish and locusts.

ואסור להעלותו עם הגבינה על השלחן חוץ מבשר דגים וחגבים…

And it is forbidden to bring it up with cheese on the table, except for the meat of fish and locusts….

When discussing cooking in the kitchen, the text refers to milk; but then, when it turns to eating at the table, cheese is the milk to which it refers. (Cheese, a coagulated dairy product, was the most common form in which milk was consumed in the ancient world.) This move from milk to cheese highlights the fact that the rabbis read Deuteronomy 14:21 and related texts as a general law: all milk, and all milk products, are forbidden to be cooked and/or consumed with all meat.

But what about fowl? M. Hullin 8:1 continues:

העוף עולה עם הגבינה על השלחן ואינו נאכל דברי בית שמאי

Fowl may go up with cheese on the table, but it may not be eaten; the words of the House of Shammai.

ובית הלל אומרים לא עולה ולא נאכל.

But the House of Hillel says: It may neither go up, nor may it be eaten…

Thus, the Houses of Shammai and Hillel debate whether fowl can be brought up to the table with cheese, but not whether they can be eaten together.

… But Is Fowl “Meat”?

While the Houses of Shammai and Hillel agree that fowl cannot be eaten with cheese, not all rabbis agreed. For example, just a few mishnayot later, we read (m. Hullin 8:4, emphasis added):

…רבי עקיבא אומר חיה ועוף אינם מן התורה שנאמר לא תבשל גדי בחלב אמו שלש פעמים פרט (1) לחיה (2) ולעוף (3) ולבהמה טמאה.

… Rabbi Aqiva says: Undomesticated animal and fowl are not prohibited by the Torah, as it is said, “Don’t cook a kid in its mother’s milk,” three times [in the Hebrew Bible], to exclude (1) undomesticated animal, (2) fowl, and (3) impure domesticated animal.

רבי יוסי הגלילי אומר נאמר לא תאכלו כל נבלה ונאמר לא תבשל גדי בחלב אמו את שאסור משום נבלה אסור לבשל בחלב

Rabbi Yosi the Galilean says: It is said, “Don’t eat any carcass” [in the beginning of Deuteronomy 14:21], and it is said, “Don’t cook a kid in its mother’s milk” [at the end of Deuteronomy 14:21]: that which is forbidden on account of “carcass,” is forbidden to cook in milk.

עוף שאסור משום נבלה יכול יהא אסור לבשל בחלב

Fowl, which is forbidden on account of carcass, might one conclude that it’s forbidden to cook in milk?

תלמוד לומר בחלב אמו יצא עוף שאין לו חלב אם:

Scripture says, “in its mother’s milk,” to exclude fowl, which has no mother’s milk.

Rabbi Aqiva states that the fowl and cheese prohibition is not from the Torah (einam min ha-Torah) and that fowl is excluded from this prohibition. Similarly, Rabbi Yosi the Galilean declares that fowl has no mother’s milk (ein lo chalav em), so it simply cannot be cooked “in its mother’s milk.” To be clear, neither authority rejects the rabbinic principle that meat and milk products may not be consumed together or even appear on the same table; they simply debate what categories of animals are included and excluded from this legislation.

There’s No Communication Like Excommunication

The Talmud inherits this tension between traditions that include fowl in all meat, and those that exclude birds. Eventually, the former tradition wins the day and fowl are treated like all meat and hence not consumed with cheese. Nevertheless, several later Talmudic texts such as b. Hullin116a (cp. b. Shabbat 130a) suggest that fowl was eaten with milk. The story centers around the late tanna, Levi:

לוי איקלע לבי יוסף רישבא,

Levi visited the house of Joseph the Fowler.

אייתו לקמיה רישא דטיוסא בחלבא,

They served him a peacock’s head [cooked] in milk.

ולא אמר להו ולא מידי

He didn’t say anything to them.[8]

כי אתא לקמיה דרבי, אמר ליה: אמאי לא תשמתינהו?

When he came before Rabbi [and told him what happened, Rabbi] said to him: Why didn’t you excommunicate them?

אמר ליה: אתריה דרבי יהודה בן בתירא הוא, ואמינא, דרש להו כרבי יוסי הגלילי דאמר יצא עוף שאין לו חלב אם.

He said to him: It was the locale of Rabbi Judah b. Beterah, and I thought, perhaps he expounded for them in accordance with Rabbi Yosi the Galilean, who said: “to exclude fowl, which has no mother’s milk.”

In this anecdote, the preferred view is that a peacock and milk dish isn’t kosher and therefore, serving it is worthy of excommunication. But Levi doesn’t excommunicate his friend Joseph the Fowler (whose occupation likely isn’t coincidental) because Yosi the Galilean’s position lends potential authority to Joseph the Fowler’s practice.

Fowl and Cheese May be Eaten (only) with Abandon!

The position permitting fowl and milk products was pushed to the sidelines over the course of the Talmudic period. A great example of this phenomenon appears in a Talmudic pericope[9] in which a statement advocating this position is reworked by the redactor in such a way as to render it almost invisible (b. Hullin 104b):

תנא אגרא חמוה דרבי אבא: עוף וגבינה נאכלין באפיקורן,

Agra, the father-in-law of Rabbi Abba, taught: Fowl and cheese may be eaten with abandon.

הוא תני לה והוא אמר לה: בלא נטילת ידים ובלא קינוח הפה.

He taught it and explained it: [“With abandon” means] without washing the hands and without wiping the mouth [between eating fowl and cheese].

Reading this text as a whole, you almost miss what has happened. But a redaction-critical approach suggests that the text that Agra taught (“Fowl and cheese may be eaten with abandon”) was a stand-alone text which simply meant: “Fowl and cheese may be eaten together; it’s totally kosher.” But Agra, or the Talmud in his name, takes this tradition and modifies it with an “official explanation,” that this only means that one can be eaten after the other without hand and mouth washing, but not at the same time.[10]

This interpretational sleight of hand continues with the inclusion of a (now seemingly relevant) story:

רב יצחק בריה דרב משרשיא איקלע לבי רב אשי, אייתו ליה גבינה – אכל, אייתו ליה בשרא אכל, ולא משא ידיה;

Rav Isaac the son of Rav Mesharshiya visited Rav Ashi’s house. They brought him cheese, [and] he ate. [Then] they brought him meat, [and] he ate, and he did not wash his hands [in between].

אמרי ליה: והא תאני אגרא חמוה דרבי אבא עוף וגבינה נאכלין באפיקורן,

They said to him: But did not Agra, the father-in-law of Rabbi Abba, teach: “Fowl and cheese may be eaten with abandon”?!

עוף וגבינה – אין, בשר וגבינה לא!

[Does not this imply:] fowl and cheese, yes; [but] meat and cheese, no?

אמר להו: הני מילי – בליליא, אבל ביממא – הא חזינא.

He said to them: This applies only at night, but during the day I can see.

The original ruling that fowl may be eaten together with cheese is not even considered, and in its place, the reinterpretation is taken as a starting point in this story. In other words, they quote the words “fowl and cheese may be eaten with abandon,” but all the rabbis in the story take it for granted that it means “without washing hands.” It is thus a given in this story that Agra’s statement assumes that fowl and cheese are actually forbidden to be eaten together, the very opposite position of the one it originally espoused!

Don’t Get Carried Away

Recognizing the tension between the verse and the rabbinic law, Maimonides attempts to explain the rabbinic logic for the fowl-as-meat rule while taking into account what the verse appears to mean (Mishneh Torah, Ma’akhalot ’Assurot 9:4):

וכן בשר חיה ועוף בין בחלב חיה בין בחלב בהמה אינו אסור באכילה מן התורה

Similarly, the meat of a non-domesticated animal and fowl, whether [cooked] in the milk of a non-domesticated animal or in the milk of a domesticated animal, is not forbidden to eat by the Torah.”

לפיכך מותר לבשלו ומותר בהנייה,

Therefore, it is permitted to cook it [together] and it is permitted to derive benefit from it.

ואסור באכילה מדברי סופרים כדי שלא יפשעו העם ויבואו לידי איסור בשר בחלב של תורה ויאכלו בשר בהמה טהורה בחלב בהמה טהורה,

But, it is forbidden to eat by rabbinic law in order that people don’t get carried away and come to violate the biblical prohibition against milk and meat, and eat the meat of a pure domesticated animal [cooked] in the milk of a pure domesticated animal.

שהרי אין משמע הכתוב אלא גדי בחלב אמו ממש

For the literal meaning of Scripture refers only to a kid [cooked] in the milk of its actual mother.

לפיכך אסרו כל בשר בחלב.

Therefore, they forbade all meat with milk.

Maimonides acknowledges that eating fowl and cheese together does not violate the biblical commandment. The reason Maimonides gives for the rabbinic prohibition is that people can miss subtle nuances that distinguish different types of meat, and since Deuteronomy 14:21 sounds as if it only prohibits a kid in its mothers’ milk, the rabbis took the extraordinary step of prohibiting non-domesticated animals and even fowl to be consumed with milk products, in order to make absolutely sure that Jews don’t come to violate the rabbinic understanding of the biblical prohibition.

Historically speaking, it is likely that how this law was practiced shifted over time, as did the categories of what counted as meat and what did not. (Though not for all Jews; for example, Karaites saw no reason to read fowl into the prohibition of Deuteronomy 14:21.)[11] Maimonides therefore is offering a retrospective logic that provides a justification for the evolution of this law.

Chicken and Eggs: Not Ethics but Fiat

But if Jews can’t eat meat and milk together, why can they eat chicken and eggs together?

We have seen that normative rabbinic opinion prohibiting the consumption of meat with milk develops to include fowl—at least in practice—in the broader injunction in Deuteronomy 14:21 to not cook a kid in its mother’s milk. Unlike Philo, however, the rabbis decide that this biblical law is not about compassion, mercy, or kindness, but about compliance with divine rule.[12] And since, for the rabbis, the law isn’t about compassion, mercy, or kindness, then milk and eggs are not analogous. Eggs are not “milk,” so they present no problem, unless – like Philo – one is making an ethical argument, which the rabbis are not. And further, since the rabbis don’t consider eggs to be “meat,”[13] then there is no problem with cooking, eating, or deriving benefit from eggs and milk.