totle[1] says "that philosophers are in some sort lovers of fables, seeing that fable is made up of marvels." And indeed men were first led to cultivate philosophy from wondering at what they saw. For my own part, then, when I see nothing left in the uterus after intercourse to which I can ascribe the principle of generation, any more than there is in the brain anything discoverable after sensation and experience, which are the prime sources of art, and when I find the structure of both alike, I have devised this fable. Let learned and ingenious men consider of it, let the supercilious reject it, and those who are peevish and scoffing laugh if they please.
Since, then, nothing can be apprehended by the senses in the uterus after coition, and since it is necessary that there be something to render the female fruitful, and as this is probably not material, it remains for us to take refuge in the notion of a mere conception and of "species without matter" (species sine materiâ), and imagine that the same thing happens here as every one allows takes place in the brain, unless indeed there be some one "whom the gods have moulded of better clay," and made fit to discover some other efficient cause besides any of those enumerated.
Some philosophers of our time have returned to the old opinion about atoms, and so imagine that this generative contagion, as indeed all others, proceeds from the subtile emanations of the semen of the male, which rise like odorous particles, and gain an entrance into the uterus at the period of intercourse. Others invoke to their aid incorporeal spirits, such as demiurgi, angels, and demons. Others regard it as a process of fermentation. Others devise other theories. I pray, therefore, a place for this conjecture of mine until something certain is established in the matter.
Many observations have been made by me which would easily overthrow the opinions I have mentioned, so easy is it to say what a thing is not rather than what it is; this is not, however, the place to introduce them, although elsewhere it is my intention to do so. On the present occasion I shall only observe, if that which is called by the common name of "contagion," as arising from the contact of the spermatic fluid in
- ↑ Metaphys. lib. i, cap. 2.
