Editing Parmenides (section)

==== B17-18: Embryology ====
Parmenides cosmology also included medical theories: two testimonies<ref>(Aetius, [[Censorinus]] and [[Lactantius]] in A 53 and A 54)</ref> indicate that Parmenides was interested in [[embryology]], and two fragments, preserved by [[Galen]] (B17), and [[Caelius Aurelianus]] (B18) are from medical contexts.

Parmenides' theory of embryology claims that each of the sexes is conceived on a different side in the mother's womb:{{efn|on the right boys, on the left girls{{harv|DK 28B17}}}} the sex of the embryo depends, on the one hand, on the side from which it is conceived in the womb, and on the other, on the side from which the father's seed comes. But the character and traits of the begotten being depend on the mixture of masculine and feminine potencies (B18). So that:
# If the semen comes from the right side and lodges in the right side of the womb, the embryo will be a well-built and masculine man.
# If the semen comes from the left side and lodges in the left side of the womb, the result is a female with feminine features.
# When the semen comes from the left, and lodges to the right of the uterus, it gives rise to a man, but with feminine traits such as outstanding beauty, whiteness, small stature, etc.
# If the semen originates on the right and descends to the left of the uterus, this time it forms a woman, but with markedly masculine traits: virility, excessive height, etc.<ref name="Poema226">Jorge Pérez Tudela, '' Poem'', p. 226.</ref>

This medical theory exhibits similarities to the medical doctrine of [[Alcmaeon of Croton]],<ref>(DK24 B4)</ref> which conceived a "equal distribution" (ἰσονομία) of forces between man and woman in determining the child's sex,{{sfn|Kirk|Raven|Schofield|1982}} and contrasts with the later theory of [[Anaxagoras]], to whom Aristotle<ref>''[[Generation of animals|de Generatione animalium]]'', IV, I 763b 30</ref> attributes the theory that only male seed determines sex.<ref name="Poema226" />

Parmenides' association of boys with "the right" and girls with "the left" in Fragment B17, combined with the testimony of Aristotle (A52) and Aetius (A53) attribute to Parmenides the view that the masculine is associated with the cold and the dense,<ref>(Aetius V, 7, 1–7 = A53)</ref> and the feminine with the hot and diffuse,<ref>Aristotle, ''De part. an.'' 648a25 = A 52</ref> upsets the general Greek conception, which associates right with light and warm, and left with dark and cold,{{sfn|Guthrie|1979|p=90}} but resembles a Pythagorean [[Table of opposites]], leading some scholars{{efn|Burnet|1892|p=185}} to postulate that Parmenides probably carried out an outline of Pythagorean cosmology. However,  on the other hand, many of the other opposites in the Pythagorean table are never mentioned by Parmenides, there are elements completely unrelated to Pythagoreanism, such as the "rings" in fragment 12, and no ancient commentators claimed to find any traces of Pythagorean doctrine in his poem, instead the Way of Opinion is unanimously considered to be Parmenides' own invention.{{sfn|Kirk|Raven|p=391}} Another possibility is that, unlike in cosmology, Parmenides did not see masculine and feminine as pure opposites in embryology, where observation and empirical guidance allowed for a greater variety of opinions on the role of males.{{sfn|Guthrie|1979|p=90}}