“Men produce female as well as male seed. So do women. Male seed is stronger than female seed. . . . This is what happens: if the stronger seed comes from both sides, the product is male; if the weaker, then the product is female. The sex of the product is determined by whichever of the two kinds of seed prevails quantitatively. “
Hippocrates, Oeuvres Completes, ed. and trans. By E. Littre, 10 vols. (Paris, 1839-61) VII, p. 479.