My great mentor, Msgr. Robert Sokolowski, told a class of eager philosophy students many years ago that we should read Aristotle’s “Nichomachean Ethics” every year of our lives. As we grew older, he explained, new dimensions of the book would continually present themselves.

I can’t say that I’ve followed Msgr. Sokolowski’s advice perfectly, but I have indeed returned often to Aristotle’s great text for inspiration and clarification. One of the philosopher’s principal insights is that the best way to understand virtue is not through abstract study but rather by watching the virtuous man in action. Learning the moral life is, for Aristotle, something like acquiring artistic skill through apprenticeship or like becoming an actor through understudying to an established thespian. Finding a master and striving to imitate him is the key. It seems only fitting, by the way, that I learned the craft of philosophizing largely by watching Msgr. Sokolowski in action.

I thought of all of this as I watched Steven Spielberg’s latest film “Bridge of Spies.” Especially in recent years, Spielberg has emerged as a latter-day Frank Capra, a celebrator of core values and the courage required to defend them. In this most recent movie, Tom Hanks (the Jimmy Stewart of our time) plays James B. Donovan, a New York insurance lawyer who is pressed into service to provide a defense for Rudolf Abel, a man very credibly accused of spying for the Soviet Union at the height of the Cold War.

Donovan does this, not because he’s convinced Abel is innocent, but because he believes in the moral principle that, in a free society, everyone deserves a fair trial. In so doing, he exemplifies the most fundamental of the classical virtues, namely, justice. Plato famously defined justice as “rendering to each his due,” and Thomas Aquinas refined that definition as “a constant will to render to another his right.” To state it as simply as possible, it is doing the upright thing.

So Donovan defends Abel because Abel is owed this privilege; to give him legal counsel is due to him. There is a bracing objectivity to this characterization of justice, especially important in our time when so much of the moral life is construed as a form of subjective expressivism: to be righteous is to be true to oneself. Quietly going about his defense of Abel, Donovan demonstrates what being true to another looks like.

Now justice remains an abstraction unless the virtuous person has the canniness to do the just thing in the right way and the right time. The tradition refers to this moral know-how as prudence—and Donovan has it in spades. In the courtroom, he uses his knowledge of the law to make the most persuasive case for his client, and in the judge’s chambers, he employs his understanding of human nature to finesse the morally compromised judge himself. Watching Donovan in action helps us to appreciate how prudence is not mere practicality, still less a compromise of moral purity, but an indispensable feature of the moral project, indeed the “queen of the cardinal virtues” according to Aquinas.

Justice is typically threatened by counterforces that come from both within and without. To withstand the first, we require the virtue of temperance and to withstand the second, we need the virtue of courage. So my desire for food, drink, sex or physical comfort can sometimes prove so powerful that it compromises my capacity to do the right thing. Think of someone caught in an addictive pattern. He knows that his compulsive need for alcohol will result in his neglect of basic family responsibilities, but he drinks anyway; or he realizes that breaking his marriage vows will destroy his relationship with his wife, but he nevertheless commits adultery.

What is needed in both cases is the ordering of sensual desire to justice, which is called temperance. It is regrettable that the term has a fussy, Victorian overtone, signaling a puritanical disdain for pleasure. Authentic temperance doesn’t suppress pleasure, but it subordinates it to a higher moral end. Donovan displays this virtue when he finds himself in massively uncomfortable surroundings while on a mission to free American prisoners in Berlin. As he waits to engage his interlocutors, he endures bad food, extreme cold, terrible accommodations, and the constant threat of arrest. Were his inner feelings not under control, he would never have been able to do the right thing at the right time.

When menaces to justice come from the outside, they have to be met by courage. So a soldier knows that engaging the enemy is what is called for, but he is gripped by fear of injury or death. Fortitude is the virtue that empowers him.

After taking on the responsibility of defending Abel, Donovan is met by pointed opposition from friends, family, co-workers and even an agent of the CIA. As the trial comes to its climax, unseen enemies pepper his home with gunfire while his children are watching television. The overwhelming majority of people would have backed away from their moral responsibility at this point, preferring safety to integrity. That Donovan presses on witnesses to his rather extraordinary courage.

Just after the conclusion of his trial, Abel turned to Donovan and muttered a phrase in Russian. When his lawyer asked what this means, Abel looked at Donovan with admiration and said, “It means ‘the standing man.’” The person of virtue is the one who stands for something and who has the capacity to stand firm in the face of threats. To understand the nature of virtue, we should, as Aristotle suggested, watch the virtuous man in action. We could do a lot worse than to study Spielberg’s latest film.