-The Torah was mistaken about the female contribution to conception
The first verse of our parsha (Leviticus 12:2) speaks of a woman giving birth. However, prior to giving birth the woman is said to tazria - from the root zera which means seed or semen. Thus, the Torah seems to be telling us that a woman seminates (releases seed) in order to become pregnant. This, we now know, is incorrect. Rather, a woman's ovaries produce eggs that are fertilized by sperm at conception. Is this a case of modern science disproving a biblical verse?
In order to understand the approaches of the commentators, let us spend a few moments on the varying notion of conception among the ancient scientists. The following is based mainly on R' David M. Feldman's Birth Control in Jewish Law, chapter 7.
Aristotle (Generation of Animals, 1:20, 2:3) taught that a baby is created from a woman's blood and a man's sperm. Tertullian was of the opinion that a woman is merely a repository of the male seed - a place that nurtures the baby placed in it. This view is reflected in the writings of Philo, among others. Galen, the first century Roman doctor whose influence remained strong through the sixteenth century, wrote in his Seed (2:1) that women emit seed. This female seed, he claimed, is a critical part of conception.
With this in mind, we can see what the commentators said about tazria. Not surprisingly, those who were physicians or philosophers read the verse in keeping with their scientific understanding. Ramban, a doctor, followed Aristotle and explained that a fetus is formed from a woman's uteral (but not menstrual) blood which is called "seed". When the Torah speaks of a woman giving zera, it is referring to this uteral blood. In his commentary to Genesis 2:18, Ramban even refers to "the well-known controversy about conception" - whether women produce or are given seed.
Ralbag, however, followed Galen that a woman produces seed that prepares the feminine substance to be acted upon by the male seed. This, he explained, is what tazria means. A woman actually produces seed in order to become impregnated.
Rambam, the famous physician and philosopher, discussed women's anatomy based on his surgical experience in his commentary to Mishna, Niddah 2:5. There, he described a woman's ovarian ducts in which her seed ripens. Clearly, as a physician he was basing his comments on both his own medical experience and, more importantly, the prevailing medical view of the time. Presumably, Rambam would agree with Ralbag's explanation of tazria - that a woman produces seed.
However, we must remember that this is all commentary. It is an attempt - by great sages - to determine the precise meaning of a specific word in the Torah. These commentaries are clearly based on specific medical theories and if these theories are incorrect then these commentaries are as well (see Chatam Sofer, Niddah 18a). However, there are other explanations of this biblical word that are not based on ancient medical theories.
Onkelos translated tazria as taadi - "is made to carry" or "conceives". R' Saadia Gaon in his Arabic translation of the Torah rendered the word similarly. Rashbam explained tazria as simply titaber - "becomes pregnant". These were not commentators who were trying to defend the Torah from a scientific attack. Quite the opposite. They could have easily explained the verse based on Galen's dominant theory that women generate seed. However, they were trying to render the Torah in a literal fashion and selected "conceive" as the literal meaning of tazria.
Somewhat surprisingly, R' Yitzchak Abarbanel, the famous philosopher and exegete, did not follow any ancient Greek medical theory. Rather, he interpreted tazria as referring to creating children because "a woman's seed is her children". See also the commentaries of R' David Tzvi Hoffman and R' Shimshon Rafael Hirsch who pointed to mazria in Genesis 1:11 where it has a meaning of sprouting.
In 1672, Reinier de Graaf discovered what were later called Graafian follicles on the surface of the ovary. He argued that these particles traveled from the ovary to the womb and acted as an egg - not like seed. This implied that the source of life is a woman's egg. However, Anthony van Leeuwenhoek in 1677 argued the exact opposite based on his examination of sperm cells through a crude microscope. He claimed that male sperm, rather than female eggs, are the core of life. These two theories remained in conflict until 1827 when Carl Ernest von Baer identified the human ovum. This led to further discoveries so that by the end of the nineteenth century it was firmly established that female egg cells, the core of life, are fertilized by male sperm cells.
In the interim period between 1672 and 1827, when the debate between the "ovulists" and the "spermatists" (as they were called) raged, we find two rabbis who were very up-to-date with the research. R' Yaakov Emden wrote in his Iggeret Bikoret p. 2b (first published in 1736) that "modern researchers do not postulate a need for female seed in reproduction... since they discovered through the microscope and many experiments that man and other creatures are formed by an egg lodged in the ovary in the woman, which constitutes the substance of the fetus..." R' Yaakov Emden was evidently an "ovulist" and was later proven correct.
R' Pinchas Halevy Horowitz, the author of Haflaah, brought both opinions in his Sefer Habrit (published in 1797). In vol. 1 ch. 17 he wrote, "Some experts have written that all man's features are in potentia in the egg... but others write that in the male sperm is the form of a miniature man." Without showing a preference between the two, R' Horowitz quoted the then-current scientific views of both the "ovulists" and the "spermatists".
The words of the Torah do not contradict science. Some scholars tried to explain the Torah based on what was then current science but such explanations are always tentative. We have seen that other explanations were offered and that rabbis did not shy away when medical understanding changed. Rather than science contradicting Torah, it has helped clarify the true meaning of the word tazria
Last revised: 2/6/02
© Aishdas 2002