Wisdom from the Early Stoics, Zeno of Citium 79

It is a tenet of the Stoics that between virtue and vice there is nothing intermediate, whereas according to the Peripatetics there is, namely, the state of moral improvement. 

For, say the Stoics, just as a stick must be either straight or crooked, so a man must be either just or unjust. 

Nor again are there degrees of justice and injustice; and the same rule applies to the other virtues. 

Further, while Chrysippus holds that virtue can be lost, Cleanthes maintains that it cannot. According to the former it may be lost in consequence of drunkenness or melancholy; the latter takes it to be inalienable owing to the certainty of our mental apprehension. 

And virtue in itself they hold to be worthy of choice for its own sake. At all events, we are ashamed of bad conduct as if we knew that nothing is really good but the morally beautiful. 

Moreover, they hold that it is in itself sufficient to ensure well-being: thus Zeno, and Chrysippus in the first book of his treatise On Virtues, and Hecato in the second book of his treatise On Goods: 

“For if magnanimity by itself alone can raise us far above everything, and if magnanimity is but a part of virtue, then too virtue as a whole will be sufficient in itself for well-being—despising all things that seem troublesome.” 

Panaetius, however, and Posidonius deny that virtue is self-sufficing: on the contrary, health is necessary, and some means of living and strength. 

—Diogenes Laërtius, 7.127-128