Is there a Jewish midrash, kabala, chasiddut or commentary addressing Chazal's understanding of the cause and purpose of menstruation?

Not just that is it a curse, that blood comes out, but with more details. For example, an explanation from which it is also understood why it does not happen before puberty, during pregnancy and nursing, and in old age. Is it related with the ability to get pregnant? Some claim that "before the 19th Century, doctors didn’t realize periods were even linked to ovulation." So what was the perspective of Jewish Rabbis?

I am not looking for explanations based on modern science.

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    Jan 4, 2019 at 18:04

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Niddah 9a

תניא נמי הכי דם נעכר ונעשה חלב דברי ר"מ רבי יוסי אומר אבריה מתפרקין ואין נפשה חוזרת עליה עד עשרים וארבע חדש א"ר אלעאי מאי טעמא דר"מ דכתיב מי יתן טהור מטמא לא אחד

So it was also taught: The menstrual blood is decomposed and turns into milk; so R. Meir. R. Jose stated: Her limbs are disjointed and her natural strength does not return before twenty-four months. R. Elai explained: What is R. Meir's reason? That it is written, Who can bring a clean thing49 from out of an unclean? Is it not the Only One? (Soncino translation)

R. Meir is of the opinion that the menstrual blood becomes the milk that a woman produces. R. Ezekiel Landau elaborates on this in his commentary to a different Talmudic passage:

Tzlach Berachot 10a

ונלע"ד דההתחלת הפיכת הדם לחלב מתחיל מימי העיבור ולכן גם אז אין הנשים רואות דם כלל והחוש יעיד על זה דרוב הנשים עוברות וכמעט כולם כשמגיעים לחדשים האחרונים הסמוכים ללידה כבר יש להם חלב בדדיהן ומה לי להביא ראיה מן החוש שלנו והדבר מפורש במס' יבמות דף מ"ב ע"א דקאמר התם וכי מלו שלשה חדשים לבדוק ופירש רש"י לבדוק בדדיה כדרך נשים וכו' הרי שדרך נשים עוברות שתיכף כשהוכר העובר יש להם חלב בדדיהן וא"כ גם פסיקת דם נדה שבימי העיבור הוא משום דדם נעכר ונעשה חלב (וברש"י במס' בכורות לא משמע כן) ואמנם החלב שבעת ההיא אינו לצורך מזון העיבור בשעתו במעי אמו שהרי אז הוא אוכל ממה שאמו אוכלת ושותה ממה שאמו שותת כמפורש במס' נדה דף ל' ע"ב אבל הוא הכנה למזונו אחר שיצא לאויר העולם ויצטרך לינק

And it seems to me that the start of the transformation of the blood to milk begins from the days of pregnancy, and therefore then too women do not see blood at all. And our senses testify to this – most pregnant women, practically all of them, when they reach the later months near the birth they already have milk in their breasts. And what do I need to adduce a proof from our senses? It is explicit in Masechet Yevamot 42a, where it says "when the three months will have been fulfilled she might be examined" and Rashi explains to examine by her breasts like the way of women etc. Behold the way of pregnant women is that immediately when the fetus is recognizable, they have milk in their breasts. And if so, the cessation of the menstrual blood during the days of pregnancy is because the blood has decomposed and turned into milk (though Rashi in Masechet Bechorot implies not so). However, the milk of that time is not for the sake of nourishing the fetus during its time in its mother's womb, because at the point it eats from what the mother eats and it drinks from what the mother drinks, as is explained in Masechet Niddah 30b. Rather, it is a preparation for its nourishment after it exits into the air of the world and needs to nurse.

Based on this, one could perhaps argue that the Sages (according to R. Meir) viewed the purpose of the blood as generating milk, and when a woman is not pregnant/nursing and there is no need for the blood to transform into milk, it simply gets discharged as blood. Thus, the purpose of menstruating was to get rid of the unnecessary blood.

  • 1
    +1 Greatly appreciated, in davinchis art he made pipes going from the uterus to the breasts
    – hazoriz
    Jan 4, 2019 at 19:49
  • I guess they considered it needed for the fetus,
    – hazoriz
    Jan 4, 2019 at 20:16
  • 2
    There you go. Scientific reasoning from ancient and medieval times at its best. Lots of our science/medical knowledge will be just as outdated in a few hundred years, if not a few dozen.
    – Gary
    Jan 5, 2019 at 0:49
  • What Rashi is (וברש"י במס' בכורות לא משמע כן) reffering to
    – hazoriz
    Jan 6, 2019 at 16:56
  • @hazoriz I think ד"ה ואין נפשה on 6b (linked in the answer).
    – Alex
    Jan 6, 2019 at 16:59

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