and from this proceeds virtue, which is defined as the perfection of reason: which they think is to be gradually developed day by day. Those things, too, which the earth produces have a sort of gradual growth towards perfection, not very unlike what we see in animals. Therefore we say that a vine lives, and dies; we speak of a tree as young, or old; being in its prime, or growing old. And it is therefore not inconsistent to speak, as in the case of animals, of some things in plants, too, being conformable to nature, and some not: and to say that there is a certain cultivation of them, nourishing, and causing them to grow, which is the science and art of the farmer, which prunes them, cuts them in, raises them, trains them, props them, so that they may be able to extend themselves in the direction which nature points out; in such a manner that the vines themselves, if they could speak, would confess that they ought to be managed and protected in the way they are. And now indeed that which protects it (that I may continue to speak chiefly of the vine) is external to the vine: for it has but very little power in itself to keep itself in the best possible condition, unless cultivation is applied to it. But if sense were added to the vine, so that it could feel desire and be moved by itself, what do you think it would do? Would it do those things which were formerly done to it by the vine-dresser, and of itself attend to itself? Do you not see that it would also have the additional care of preserving its senses, and its desire for all those things, and its limbs, if any were added to it? And so too, to all that it had before, it will unite those things which have been added to it since: nor will it have the same object that its dresser had, but it will desire to live according to that nature which has been subsequently added to it: and so its chief good will resemble that which it had before, but will not be identical with it; for it will be no longer seeking the good of a plant, but that of an animal. And suppose that not only the senses are given it, but also the mind of a man, does it not follow inevitably that those former things will remain and require to be protected, and that among them these additions will be far more dear to it than its original qualities? and that each portion of the mind which is best is also the dearest? and that its chief good must now consist in satisfying its nature, since intellect and reason are by far the most excellent parts
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