The order of the soul subsists in such a way, that one part of it is the reasoning power, another is anger, and another is desire. And the reasoning power, indeed, has dominion over knowledge; anger over impetus; and desire intrepidly rules over the appetitions of the soul. When therefore these three parts pass into one, and exhibit one appropriate composition, then virtue and concord are produced in the soul. But when they are divulsed from each other by sedition, then vice and discord are produced in the soul. It is necessary, however, that virtue should have these three things, viz. reason, power, and deliberate choice. The virtue, therefore, of the reasoning power of the soul is prudence; for it is a habit of judging and contemplating. But the virtue of the irascible part, is fortitude; for it is a habit of resisting, and enduring things of a dreadful nature. And the virtue of the epithymetic or appetitive part is temperance; for it is a moderation and detention of the pleasures which arise through the body. But the virtue of the whole soul is justice. For men indeed become bad, either through vice, or through incontinence, or through a natural ferocity. But they injure each other, either through gain, or through pleasure, or through ambition. Vice, therefore, more appropriately belongs to the reasoning part of the soul. For prudence indeed is similar to art; but vice to pernicious art. For it invents contrivances for the purpose of acting unjustly. But incontinence rather pertains to the appetitive part of the soul. For continence consists in subduing, and incontinence in not subduing pleasures. And ferocity pertains to the irascible part of the soul. For when some one, through acting ill from desire, is gratified not as a man should be, but as a wild beast, then a thing of this kind is denominated ferocity. The effects also of these dispositions are consequent to the things for the sake of which they are performed. For avarice is consequent to vice; but vice is consequent to the reasoning part of the soul. And ambition, indeed, follows from the irascible part; and this becoming excessive, generates ferocity. Again, pleasure pertains to the appetitive part; but this being sought after more vehemently, generates incontinence. Hence, since the acting unjustly is produced from so many causes, it is evident that acting justly is effected through an equal number of causes. For virtue, indeed, is naturally beneficent and profitable; but vice is productive of evil, and is noxious.

Since, however, of the parts of the soul, one is the leader, but the other follows, and the virtues and the vices subsist about these, and in these; it is evident that with respect to the virtues also, some are leaders, others are followers, and others, are composed from these. And the leaders, indeed, are such as prudence; but the followers are such as fortitude and temperance; and the composites from these, are such as justice. The passions, however, are the matter of virtue; for the virtues subsist about, and in these. But of the passions, one is voluntary, but another is involuntary. And the voluntary, indeed, is pleasure; but the involuntary is pain. Men also, who have the political virtues, give intension and remission to these, co-harmonizing the other parts of the soul, to that part which possesses reason. But the boundary of this co-adaptation, is for intellect not to be prevented from accomplishing its proper work, either by indigence, or excess. For that which is less excellent, is co-arranged for the sake of that which is more excellent. Thus in the world, every part that is always passive, subsists for the sake of that which is always moved. And in the conjunction of animals, the female subsists for the sake of the male. For the latter sows, generating a soul; but the former alone imparts matter to that which is generated. In the soul however, the irrational subsists for the sake of the rational part. For anger and desire are co-arranged in subserviency to the first part of the soul; the former as a certain satellite, and guardian of the body; but the latter as a dispensator and provident curator of necessary wants. But intellect being established in the highest summit of the body, and having a prospect in that which is on all sides splendid and transparent,[65] investigates the wisdom of [real] beings. And this is the work of it according to nature, viz. having investigated, and obtained the possession [of truth] to follow those beings who are more excellent and more honorable than itself. For the knowledge of things divine and most honorable, is the principle, cause, and rule of human blessedness.