which conspire to one and the same action though diverse in faculty and use; for some are principal instruments in the action; some are indispensable to it, without them it could not take place; some secure its better performance; and some, in fine, are extant for the safety and preservation of everything else." He also shows it to be an agent, when from Aristotle and Galen he lays down the two actions of the egg, viz. : "the generation of the chick, and the growth and nutrition of the pullet." At the conclusion he expresses himself clearly in these words : " In the works of nature we see conjunct and one, the artificer, the in- strument, and the matter; the liver, for instance, is both the agent and the instrument for the production of the blood; and so every part of the body ; Aristotle, 1 therefore, said well that the moving powers were not easily distinguished from the in- struments. In artificial things, indeed, the artificer and the instrument are distinct, as much so as the workman and his hammer, the painter and his pencil. And the reason adduced by Galen 2 is this : that in things made by art the artificer is without the work; in natural things, again, the artificer is within it, conjunct with the instruments, and pervading the whole organization."
To this I add these perspicuous words of Aristotle. 3 " Of extant things some are consistent with nature, others with other causes. Animals and their parts, and plants, and simple bodies, as earth, fire, air, and water, consist with nature, and are allowed universally to do so; but these bodies differ entirely from those that do not consist with nature. For whatsoever consists with nature is seen to have within itself a principle of motion and of rest, now according to place, now according to increment and decrement, and again according to change. A couch or litter, a garment, and other things of the same description, however designated, inasmuch as they are made by art, have no inherent faculty of change; but inasmuch as they are made of [wood, or] earth, or stone, [or of wool, silk, or linen,] or of mixtures of these, they have such a faculty. As if nature were a certain principle and cause wherefore that should move and be at rest in which she inheres originally, independently, and not by acci- dent. I say, particularly, not by accident, because it might happen that one being a physician should himself be the cause 1 De Gener. Anira. lib. ii, cap. 4. 2 De form. feet. 3 Phys. lib. i, cap. 1.
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