What is virtue? In the earliest Greek writings virtue was most often expressed as the kind of manliness that makes a soldier brave in battle, that gives him courage to stand against the odds. A man demonstrated his virtue in his military valor.
For example, when Cyrus and the armies of Persia were fighting their way across Asia Minor, they met pockets of fierce resistance. In the plain of Xanthus the Lycians met him with virtue, as an ancient historian described it, with heroic deeds of valor. When driven back into their city, they gathered their wives, children, servants, and possessions into the citadel and set the citadel on fire. Then the men marched out to fight and die. Such was virtue in the days of old.
By the time of Socrates, however, the Greek word for virtue (arete --¬ ar eh TAY) came to focus less on military courage and more on inward valor, on moral excellence. The virtue of a judge, said Socrates, is to be just; the virtue of an orator is to speak the truth. In a burst of philosophical optimism, Plato said that if only a man attains true insight into what is virtuous, he will do it.
But alas -- virtue is not so easily and automatically attained! Men do not become morally pure just because they know what is virtuous. Men must come to admire and believe in the One who called them through his own glory and virtue (2 Peter 1:3) and then give diligence to add virtue to their faith in him (2 Peter 1:5). They must focus attention on whatever is virtuous (Philippians 4:8) so they can show forth the virtues of him who called them out of darkness into his marvelous light (1 Peter 2:9).
So what is virtue? It is a beautiful composite of courage, valor, moral excellence, and truth. But note well this closing fact: it is one thing to be able to define it, but it is a better thing to do it!