To the third class then belonged such things as life and death, health and sickness, pleasure and pain, beauty and ugliness, strength and weakness, honour and dishonour, wealth and poverty, victory and defeat, nobility and baseness of birth.
Good was defined as that which benefits. To confer benefit was no less essential to good than to impart warmth was to heat. If one asked in what 'to benefit' lay one received the reply that it lay in producing an act or state in accordance with virtue, and similarly it was laid down that 'to hurt' lay in producing an act or state in accordance with vice.
The indifference of things other than virtue and vice was apparent from the definition of good which made it essentially beneficial. Such things as health and wealth might be beneficial or not according to circumstances; they were therefore no more good than bad. Again, nothing could be really good of which the good or ill depended on the use made of it, but this was the case with things like health and wealth.
The true and only good then was identical with what the Greeks called 'the beautiful' and what we call 'the right'. To say that a thing was right was to say that it was good, and conversely to say that it was good was to say that it was right; this absolute identity between the good and the right and, on the other hand, between the bad and wrong, was the head and front of the Stoic ethics. The right contained in itself all that was necessary for the happy life, the wrong was the only evil, and made men miserable whether they knew it or not.
As virtue was itself the end, it was of course choiceworthy in and for itself, apart from hope or fear with regard to its consequences. Moreover, as being the highest good, it could admit of no increase from the addition of things indifferent. It did not even admit of increase from the prolongation of its own existence, for the question was not one of quantity, but of quality. Virtue for an eternity was no more virtue, and therefore no more good, than virtue for a moment. Even so one circle was no more round than another, whatever you might choose to make its diameter, nor would it detract from the perfection of a circle if it were to be obliterated immediately in the same dust in which it had been drawn.
To say that the good of men lay in virtue was another way of saying that it lay in reason, since virtue was the perfection of reason.
As reason was the only thing whereby Nature had distinguished man from other creatures, to live the rational life was to follow Nature.
Nature was at once the law of God and the law for man. For by the nature of anything was meant, not that which we actually find it to be, but that which in the eternal fitness of things it was obviously intended to become.
To be happy then was to be virtuous, to be virtuous was to be rational, to be rational was to follow Nature, and to follow Nature was to obey God. Virtue imparted to life that even flow in which Zeno declared happiness to consist. This was attained when one's own genius was in harmony with the will that disposed of all things.
Virtue having been purified from all the dross of the emotions, came out as something purely intellectual, so that the Stoics agreed with the Socratic conception that virtue is knowledge. They also took on from Plato the four cardinal virtues of Wisdom, Temperance, Courage, and Justice, and defined them as so many branches of knowledge. Against these were set four cardinal vices of Folly, Intemperance, Cowardice, and Injustice. Under both the virtues and vices there was an elaborate classification of specific qualities. But notwithstanding the care with which the Stoics divided and subdivided the virtues, virtue, according to their doctrine, was all the time one and indivisible. For virtue was simply reason and reason, if it were there, must control every department of conduct alike. 'He who has one virtue has all,' was a paradox with which the Greek thought was already familiar. But Chrysippus went beyond this, declaring that he who displayed one virtue did thereby display all. Neither was the man perfect who did not possess all the virtues, nor was the act perfect which did not involve them all. Where the virtues differed from one another was merely in the order in which they put things. Each was primarily itself, secondarily all the rest. Wisdom had to determine what it was right to do, but this involved the other virtues. Temperance had to impart stability to the impulses, but how could the term 'temperate' be applied to a man who deserted his post through cowardice, or who failed to return a deposit through avarice, which is a form of injustice, or yet to one who misconducted affairs through rashness, which falls under folly? Courage had to face dangers and difficulties, but it was not courage unless its cause were just. Indeed one of the ways in which courage was defined was a virtue fighting on behalf of justice. Similarly justice put first the assigning to each man his due, but in the act of doing so had to bring in the other virtues. In short, it was the business of the man of virtue to know and to do what ought to be done, for what ought to be done implied wisdom in choice, courage in endurance, justice in assignment and temperance in abiding by ones conviction. One virtue never acted by itself, but always on the advice of a committee. The obverse to this paradox—He who has one vice has all vices—was a conclusion which the Stoics did not shrink from drawing. One might lose part of one's Corinthian ware and still retain the rest, but to lose one virtue—if virtue could be lost—would be to lose all along with it.