Donald Kagan, writing today at The Imaginative Conservative, quoted Aristotle in a piece entitled: Why We Should Study the History of Western Civilization.
Kagan recommends an examination of "the older traditions of the West that came before the modern era and to take seriously the possibility that useful wisdom can be found there, especially among the Greeks who began it all. They understood the potentiality of human beings, their limitations, and the predicament in which they live. Man is potent and important, yet he is fallible and mortal, capable of the greatest achievements and the worst crimes. He is a tragic figure, powerful but limited, with freedom to choose and act but bound by his own nature, knowing that he will never achieve perfect knowledge and understanding, justice and happiness, but determined to continue the search."
Kagan quotes Aristotle on the necessity of man to be virtuous. Here's the quote:
As man is the best of the animals when perfected, so he is the worst when separated from law and justice. For injustice is most dangerous when it is armed, and man, armed by nature with good sense and virtue, may use them for entirely opposite ends. Therefore, when he is without virtue man is the most unscrupulous and savage of the animals . . .