People look to popular culture for entertainment, even titillation, but they also look to it for moral instruction – for ideas on how to live their lives.

A case in point is a new movie, “Eragon,” about a righteous boy and his dragon fighting an evil empire. It’s a fairy tale with computer-generated special effects, and, as we shall see, fairy tales have a way of inspiring people in real life.

Many movies and television shows offer lessons in behaving badly. But much of pop culture appeals to the better angels of our nature. The recent film “Akeelah and the Bee,” for example, tells of a black girl struggling to succeed in a spelling contest.

The film was a modest box-office success, but it’s destined to live forever as a motivational tool for elementary school kids confronted with difficult challenges.

Indeed, pop culture, however trashy and violent, tends ultimately to reaffirm the moral order. In the endless profusion of cops-and-robbers shows, the good guys almost always win; in murder mysteries, the killer is invariably discovered.

Yet, the moral import of a story is often best presented when the tale is stripped to allegory, as in Aesop’s Fables, Mother Goose and the Brothers Grimm. By taking the Big Questions out of the here and now – by removing them to some distant past or to a phantasmagorical universe – it’s easier to drill home the moral of the story.

And so mega-movies such as “Star Wars,” “Gladiator,” “Lord of the Rings” and “Chronicles of Narnia” were all hits, in part because they transported audiences to a place where good and evil could be stated visually. Luke Skywalker wears white, so he’s the good guy, while Darth Vader, of course, wears black.

The moral message of such films is simple yet profound: Do right by others, don’t be evil. And, yes, be willing to fight – even die – for what you believe in. And if you are lonely in the pursuit of justice, like Superman, Spider-Man or the cowboy Shane, well, that explains why heroes are scarce. It’s not an easy life.

Other moral messages can be found, to be sure, in pop culture. But the idea of fighting for a noble cause is one of the most steady and deeply rooted themes in our civilization, and it’s no surprise that movies keep coming back to it.

In these movies, we can see chivalry – the knightly ideal of service and sacrifice – presented and exalted in various ways. And so we also can see in these movies sources of future chivalric action, because some percentage of the young and tilting audience is going to be inspired to join the military, the police or some other honor-bound institution.

Even Mel Gibson’s new film, “Apocalypto,” fits into this model: It’s about a gallant Mayan Indian fighting for his family. Like Gary Cooper in “High Noon,” he doesn’t say much; he just does the right thing. And if people must die – well, they deserved it.

Not everyone accepts Gibson’s vision, of course, let alone Gibson himself. But critics have been kind to the movie, and audiences seem to be responding. “Apocalypto” was the No. 1 movie last week at the box office.

And now comes yet another entry in the chivalry-and-special-effects genre. “Eragon,” based on the popular novels, can best be described as a pastiche of familiar cliches: one part “Lord of the Rings,” one part “Star Wars” and one part “The Karate Kid.” So although some will dismiss “Eragon” as derivative piffle, others will like it because it sticks to a revered formula. And here’s a prediction: Out there in the multiplexes, kids will be looking up at the screen and saying to themselves, “That’s the way I want to live my life.” And so back in the real world, where duty, honor and violence are real, the saga of chivalry will be renewed yet again.