3. The rational animal, however, has, in addition to its phantasial nature, also reason, which judges the phantasies, and disapproves of some and accepts others, in order that the animal may be led according to them. Therefore, since there are in the nature of reason aids towards the contemplation of virtue and vice, by following which, after beholding good and evil, we select the one and avoid the other, we are deserving of praise when we give ourselves to the practice of virtue, and censurable when we do the reverse. We must not, however, be ignorant that the greater part of the nature assigned to all things is a varying quantity among animals, both in a greater and a less degree; so that the instinct in hunting-dogs and in war-horses approaches somehow, so to speak, to the faculty of reason. Now, to fall under some one of those external causes which stir up within us this phantasy or that, is confessedly not one of those things that are dependent upon ourselves; but to determine that we shall use the occurrence in this way or differently, is the prerogative of nothing else than of the reason within us, which, as occasion offers, arouses us towards efforts inciting to what is virtuous and becoming, or turns us aside to what is the reverse.