Page:The Works of William Harvey (part 1 of 2).djvu/396

 EXERCISE THE THIRTY-THIRD.

The male and the female are alike efficient in the business of generation.

The medical writers with propriety maintain, in opposition to the Aristotelians, that both sexes have the power of acting as efficient causes in the business of generation; inasmuch as the being engendered is a mixture of the two which engender: both form and likeness of body, and species are mixed, as we see in the hybrid between the partridge and common fowl. And it does indeed seem consonant with reason to hold that they are the efficient causes of conception whose mixture appears in the thing produced.

Aristotle entertaining this opinion says } " In some animals it is manifest that such as the generator is, such is the engendered; not, however, the same and identical, not one numerically, but one specifically, as in natural things. A man engenders a man, if there be nothing preternatural in the way, as a horse [upon an ass] engenders a mule, and other similar instances. For the mule is common to the horse and the ass; it is not spoken of as an allied kind ; yet may horse and ass both be there conjoined in a hybrid state." He says farther in the same place : " It is enough that the generator generate, and prove the cause that the species be found in the matter: for such and such an entire species is still found associated with such and such flesh and bones here it is Gallias, there it is Socrates."

Wherefore if such an entire form, as a mule, be a mixture of two, viz. : a horse and an ass, the horse does not suffice to produce this form of a mule in the ' matter/ but, as the entire form is mixed, so another efficient cause is contributed by the ass and added to that supplied by the horse. That, therefore, which produces a mule compounded of two, must itself be an ' adequate efficient,' and mixed, if only ' univocal/ For ex- ample, this woman and that man engender this Socrates ; not in so far as they are both human beings, and of one and the same

1 Metaphys. lib. vii, cap. 8.