Hippocrates, who lived under Perdicas, a considerable time before Aristotle, established an opinion, which was adopted by Galen, and a great number of physicians who followed him; his opinion was, that the male and female had each a prolific fluid, and supposed, besides, that there were two seminal fluids in each sex, the one strong and active, the other weak and inactive.[A] That a mixture of the two strongest fluids produce a male child, and of the two weakest a female; so that, according to him, they each contain a male and a female seed. He supports this hypothesis by the following circumstance; that many women, who produce only girls by their first husbands, have produced boys by a second; and that men, who have had only girls by their first wives, have had boys by others. It appears to me, that if even this circumstance could be well established, it would not be necessary to give to the male and female two kinds of seminal liquor for an explanation; because it may easily be conceived, that women, who have brought forth only girls by their first husbands, and produced boys with other men, were only those who furnished more particles proper for generation with their first husband than with the second; or that the second husband furnished more particles proper for generation with the second wife than with the first; for when, in the instant of conception, the organic molecules of the male are more abundant than those of the female, the result will be a male, and when those of the female abounds a female will be produced; nor is it in the least surprising that a man should have a disadvantage in this respect with some women, while he will have a superiority over others. [A] See Hippocrates, lib. de Genitura, page 129, & lib. de diæta, page 198, Lugd. Bat. 1665, vol. I. This great physician supposes, that the seed of the male is a secretion of the strongest and most essential parts of all that is humid in the human body; and he thus explains how this secretion is made: "Venæ & nervi, he says, ab omni corpore in pudendum vergunt, quibus dum aliquantulum teruntur & calescunt ac implentur, velut pruritus incidit, ex hoc toti corpori voluptas ac caliditas accidit; quum vero pudendum teritur & homo movetur, humidum in corpore calescit ac diffunditur, & a motu conquassatur ac spumescit, quemadmodum alii humores omnes conquassati spumescunt.