The Gemara AZara, Perek 2, describes our life with our neighbours in all its gruesome ugliness. It is not difficult to imagine various locations where even today, we would feel very unsafe and vulnerable. Where the authorities charged with maintaining law and order would not pursue justice with all their resources and energies, and would turn a blind eye to injustices inflicted upon us because we are Jewish.
Take the UN if a simple example is required.
Our Sages therefore promulgated various laws to protect the community. For example, they forbade leaving beasts under the care of our neighbours, or employing a neighbour to assist as a midwife or to nurse our children.
The Ran qualifies this with a common sense argument: “It is reasonable to suppose that this decree no longer applies. These days there are laws that forbid such behaviour and these laws are enforced and transgressors are severely punished.”
The Ran then opens a discussion regarding the Kosher status of human milk. Since the Sages’ prohibition was not based upon the wet-nurse’s milk being non-Kosher but on the welfare of the baby, it is clear that the milk of the wet nurse is Kosher. This seems quite reasonable, we are unfamiliar with any Halachic framework suggesting that human milk from different people would or should have different Kosher properties.
However, the Gemara of Yevamos 114, suggests otherwise. It records that when an infant has no Jewish nurse available, it must be fed milk from any source; it is assumed that infants are all fragile and deemed to be cases of PiKuAch Nefesh. The Gemara includes nursing the infant with an neighbour. This Gemara appears to assume that only the milk of Jewish nurse is Kosher and a neighbour may nurse the infant because it is a case of PiKuAch Nefesh.
In order to resolve the apparent contradiction between the Gemara of AZara and Yevamos, some suggest that indeed only a Jewish woman’s milk is Kosher. When there is no Kosher milk for the baby, the Gemara of AZ records a dispute between Rebbi Meir who prohibits the neigbbour to nurse even when there are Jewish women overseeing the nurse and the Rabbanan who permit where there is oversight. This dispute is about evaluating risks and dangers. Clearly if there is no choice, the neighbour will nurse the child, with oversight. However, when there is a reasonable chance that a Jewish nurse can be brought from nearby, Rebbi Meir rules that this option must be explored and the “normal” infant does not face any real risk by the delay; whereas the Rabbanan urge that even this small risk must be avoided.
The Rashba however rejects the notion that only milk of a Jewish woman is Kosher. He argues that as the Gemara rules that milk of humans is Kosher [Kesuvos 60a] it is unreasonable and without precedent to suggest that some difference exists between milk of Jewish or non-Jewish women. The preference to employ Jewish nurses is Middas Chassidus, a personal preference that is predicated upon the assertion that the bond between nurse and infant encourages the infant in subtle ways.
This is supported from the Medrash that explores why Yocheved was called to nurse the infant Moshe, who had been discovered and saved by Basya the daughter of Pharoh. The Medrash explains that HKBH intervened since Moshe was to speak to HKBH it was unseemly that the same mouth be nursed from anyone but a Jewish woman.