For how is it possible for the same man to be both better and worse than himself, or to be master of himself and at the same time be mastered, if in some way or other each man were not by nature double and had not both the worse and the better within himself? This being the case, he who holds the worse in subjection to the better is Iself-controlled and better than himself, but he who permits the better part to follow and be in subjection to the intemperate and irrational part of his soul is called worse than himself and incontinent and in a state contrary to Nature. For, in accordance with Nature, it is proper that reason, which is divine, should lead and rule the irrational, which derives its origin directly from the body to which Nature has designed that it should bear a resemblance and share in the body’s passions and be contaminated by it, since it has entered into the body and has become merged with it; that this is so is shown by our impulses, Cf. Plato, Timaeus , 86 b. which arise and are set in motion toward corporeal objects and become violent or relax in keeping with the changes of the body. For this reason young men are swift and impetuous and fiery in their appetites, and stung by madness, as it were, through the abundance and heat of their blood; but in old men the source of desire, which is seated about the liver, Ibid. 71 a. is in the process of being extinguished and becoming small and weak, whereas reason increases more and more in vigour as the passionate element fades away together with the body. And this, of course, is what determines the natures of wild beasts also as regards the passions. For it is not, I presume, by the rightness or wrongness of their opinions that some of them oppose apparent dangers with valour and impetuousness whereas others have helpless flutterings and fears in their souls; but the faculties which control the blood, the breath, and the body in general cause the difference in their affections, since the emotional part springs up from the flesh as from a root and carries with it its quality and composition. But that in man his body is affected and moved together with the impulses of his passions is proved by his paleness Cf. De Libidine et Aegritudine , 6 (Bernardakis, vol. vii. p. 5). and blushing, his trembling and palpitations of the heart, and again by his cheerful and relaxed expression when in hope and expectation of pleasures. But whenever the intellect acts, not accompanied by emotion but by itself alone, the body remains in repose and at rest, neither sharing nor partaking in the activity of the mind, so long as the body does not have to deal with the emotional element or include the irrational in such activity. Consequently, this fact also makes it plain that there are two parts within us which differ from each other in their faculties.