For animals the primary impulse consists in preserving themselves, since from the beginning nature familiarizes [this] to them. For its constitution and its consciousness[1] of this is the first familiar thing to every animal, i.e being familiarized to themselves. That is the reason why animals refuse what is harmful to them and approach to what is familiar to them. For animals the first impulse is not directed toward pleasure,[2] for pleasure is just a byproduct,[3] if, in fact, there is pleasure when nature, by itself, has searched out and does not[4] acquire what fits in an animal's constitution. That is the way in which animals perceive and plants bloom. And nature does not distinguish between animals and plants when it directs the latter without impulse and sensation; even in us there are some processes which are plant-like. But since the additional faculty of impulse supervenes on animals, on the basis of which they move, it is natural for them to be governed in accordance with impulse.[5] But since reason has been given to rational beings as a more perfect governor, living correctly according to reason becomes for them[6] what is natural; for reason supervenes as a craft[7] of impulse. Therefore, Zeno also said that the end is to live in consistency with nature, which is to live according to virtue;[8] for nature leads us to virtue as well.