Meat and Milk Seperation

Greetings and blessings.

To begin with the answer, I will explain the prohibition of mixing meat and milk according to the Rishonim (early authorities) and the Kabbalists. This is a general rule regarding mixtures, as the Torah forbids wearing wool and linen together, and planting fruits and vegetables together. The reason for all of these is that the creation we see before our eyes is merely a manifestation of higher spiritual forces. Everything below has a corresponding upper root. The Creator forbade the mixing of these forces, and human actions below, by mixing meat with milk, also affect the higher forces because a person is formed from both the upper and lower realms through the soul within him. Therefore, every action a person takes—especially a Jewish person with a divine soul—also influences all upper forces. Mixing there causes spiritual disruptions to the world.

The explanations are extensive. There are also reasons based on the plain meaning, and I will cite one from the book "Kli Yakar" (Exodus 23:19):

"Do not cook a kid in its mother's milk." It is close to hear that this commandment is related to the prohibition of mixtures and the blending of forces, for it is known that the meat of the embryo is born from the blood of the female, which brings forth all redness, as that is its source. Likewise, the milk of the animal also comes from the blood's source, for the blood becomes contaminated and turns into milk. According to this, from the animal's blood comes the meat of the embryo and the milk, for they should be separated, and it is not proper to mix them again through cooking or eating. The reason for this mixing applies to all animal flesh, and the kid in its mother's milk is specifically mentioned because it fundamentally represents this mixing.

His words clarify that the Torah uses the phrase 'in its mother's milk' even though the prohibition also applies to other milk because the reason for the commandment is not to mix the meat and milk that come from the same source. In Hashem's wisdom, they were separated—one for whiteness and the other for redness—and they should not be mixed again. To explain where the meat and milk originated from, the Torah specified the mother's milk, as both the calf born and the milk come from the same source.

In the secrets of the Torah, it is explained that redness is the source of the attribute of judgment in the world, while whiteness is the source of the attribute of mercy, and it is improper to mix these attributes. When a person mixes the meat stemming from the source of redness with the power of whiteness from the drink of milk, he nullifies and weakens the power of mercy, and it should not be done.

You are correct that the written Torah only forbids the meat of a beast with milk, and the prohibition against cooking and eating poultry—which does not nurse—with milk is a rabbinic prohibition instituted to guard these laws, as the sages were commanded that way in the Torah. When they saw that people were faltering in the prohibitions of meat and milk, they added a fence and guard to prohibit even poultry with milk. After they forbade it to us, we are obligated to observe the commandments of the sages, as it is written in the portion of Shoftim: 'You shall not turn aside from the word that they tell you, right or left.'

The reason that the sages deemed it appropriate to add and forbid even poultry was precisely for the reason mentioned above: since the Torah wrote in the language of prohibition the phrase 'a kid in its mother's milk' for the reason it deemed appropriate, people interpreted that there is no prohibition except for the meat with the milk of the mother, and consequently they disregarded the prohibition of meat and milk. Therefore, the sages came and in order to safeguard the Torah's prohibitions, they also forbade even poultry that does not have a nursing mother with milk, so that from now on people would not falter in eating the flesh of animals with milk that is not from the mother, given that they even forbade the consumption of poultry that does not nurse with milk.

These matters are written in the Mishneh Torah of Rabbi Moshe ben Maimon, and this is his language: 'Similarly, poultry, whether with the milk of a beast or the milk of a non-beast, is not prohibited to eat from the Torah; therefore, it is permitted to cook it, and it is permitted for enjoyment, but it is forbidden to eat it according to the words of the sages—to prevent the people from transgressing the Torah prohibition of meat and milk by eating pure meat with pure milk, for it does not seem that the text refers to anything but a kid in its mother's milk specifically. Therefore, all meat with milk is forbidden.'

Best wishes - Menashe Yisrael