Page:The Works of William Harvey (part 1 of 2).djvu/386

 the rising to the setting, in his passage over the various regions of the earth, so also is there a vis enthea, a divine principle in- herent in our common poultry, showing itself now as the plastic, now as the nutritive, and now as the augmentative force, though it is always and at all times present as the conservative and vegetative force, and now assumes the form of the fowl, now that of the egg; but the same virtue continues to inhere in either to eternity. And although some animals arise spontaneously, or as is commonly said from putrefaction, and some are produced from the female alone, for Pliny 1 says: "in some genera, as in certain fishes, there are no males, every one taken being found full of roe ;" still whatever is produced from a perfect egg is so in virtue of the indispensable concurrence of male and female. Aristotle 2 consequently says : " the grand principles of generation must be held to be the male and the female ;" the first two prin- ciples of the egg are therefore the male and the female ; and the common point or conception of these is the egg, which combines the virtues of both parents. We cannot, in fact, conceive an egg without the concurrence of a male and female fowl, any more than we can conceive fruit to be produced without a tree. We therefore see individuals, males as well as females, existing for the sake of preparing eggs, that the species may be perennial, though their authors pass away. And it is indeed obvious, that the parents are no longer youthful, or beautiful, or lusty, and fitted to enjoy life, than whilst they possess the power of pro- ducing and fecundating eggs, and, by the medium of these, of engendering their like. But when they have accomplished this grand purpose of nature, they have already attained to the height, the a/c^urj of their being, the final end of their existence has been accomplished ; after this, effete and useless, they begin to wither, and, as if cast off and forsaken of nature and the Deity, they grow old, and, a-weary of their lives, they hasten to their end. How different the males when they make them- selves up for intercourse, and swelling with desire are excited by the venereal impulse ! It is surprising to see with what passion they are inflamed; and then how trimly they are feathered, how vainglorious they show themselves, how proud of their strength, and how pugnacious they prove ! But, the grand business of life accomplished, how suddenly, with failing strength and pristine 1 Hist. Natur. lib. ix, cap. 16. 2 De Gen. Anim. lib. i, cap. 2.