Hence it is more difficult to bear prosperity in a becoming manner than adversity. For all men when they continue in adversity, are seen for the most part to be moderate and orderly in their manners; but in prosperity they are brave, magnificent, and magnanimous [when they bear it in a becoming manner]. For adversity has the power of contracting and depressing the soul; but prosperity, on the contrary, elevates and expands it. Hence all those that are unfortunate, are in their manners cautious and prudent; but those that are fortunate are insolent and confident. But the boundary of prosperity, is that which a good man would deliberately choose to co-operate with him in his own proper actions; just as the [proper] magnitude of a ship, and the [proper] magnitude of a rudder, are such as will enable a good pilot to sail over a great extent of sea, and to accomplish a great voyage. An excess of prosperity, however, is not naturally adapted to be vanquished by, but to vanquish the soul. For as a [very] splendid light causes an obscuration of sight in the eyes; thus also excessive prosperity darkens the intellect of the soul. And thus much may suffice concerning prosperity.
FROM THEAGES, IN HIS TREATISE ON THE VIRTUES.
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.