Lucas captivated audiences on yet another level with one astonishing premise: The Force, which emanates from all life and is both accessible to all and inborn more strongly in some. The Force has a good side, accessed by the Jedi knights, like Obi Wan Kenobe, serving the rebel alliance. It also has the dark side, represented by Darth Vader, serving the Imperial Empire and its powerful hooded emperor. The Force not only added an all-purpose explanation for fantastic accomplishments but a mystical and spiritual dimension largely absent from a 1970s American culture dominated by the rigid and linear materialism of economics and science.

In the third film of this trilogy, "'>Return of the Jedi," the Empire is overthrown by Luke Skywalker and an underdog alliance with more virtue than technology, in a final battle fought partly in space, and partly on a green world that looks very much like Eureka, California. It was a satisfying ending, and everyone identified. Released in 1983, its message inspired New Age advocates and environmentalists, and also President Ronald Reagan, who began referring to the Soviet Union as the Evil Empire, and proposed a missile defense system that was quickly dubbed "Star Wars."

But Lucas had a larger, more complex and perhaps less comfortable story in mind. Darth Vader, the black-clad, half-machine villain skulking in the darkness, turned out to be the evil father of Luke Skywalker and his twin sister, Leia. Even though Vader turns away from the dark side before he dies, the question was raised: how does evil father good? The answer given in the new prequel trilogy is provided by the less literal reversal: how good fathers evil.

Beginning with '>"The Phantom Menace" in 1999, Lucas explores the rise and fall of Anakin Skywalker, who will become Darth Vader in "Revenge of the Sith." (The Sith are revealed as the dark side equivalent of the Jedi.) In the past several years, DVDs of all five prior Star Wars films were released(including "'>Star Wars II: Attack of the Clones" from 2002) with commentary tracks that included George Lucas talking in his low-key Modesto way about the arc of these two trilogies.

In between chat on mechanics of filmmaking (the Bantha is really an elephant in costume) Lucas reveals how deliberate his thematic thinking has been. The evil Empire figures wear black and white, because they represent a black-and-white world view of self-righteous certainties. The rebels are clothed in earth-tones, representing the organic complexities. The same situations and motifs recur purposefully; the difference is in the choices characters make each time.

In "Jedi" we saw Luke reject the temptations of the dark side's power by restraining his anger and hate. The entire prequel trilogy may be seen as a demonstration of how someone makes the opposite choice, and Lucas has clearly tried to make Anakin Skywalker sympathetic as well as strong. To up the ante, Lucas even gives him the equivalent of a virgin birth, born of the mating of a woman and the Force itself. He is "the chosen one."

Anakin is hotblooded but his reactions seem reasonably provoked: he is taken from his mother as a child, and as a young man sees her killed by kidnappers. He is forbidden the woman he loves. His personal descent is mirrored in the politics Lucas spends a lot of time elaborately setting up, with the apparently reasonable and reactive, step-by-step transformation of the democratic Republic into the dictatorial Empire, though it is being manipulated by one of its own.

The society and the hero that think themselves good but transform themselves into evil is a bold theme that resonates in post-9/11 America. Lucas says forthrightly that his point of view was formed during the Vietnam war. Though of course he could not have predicted that this film would open while the U.S. has an army of occupation in Iraq, it inevitably applies, especially considering how officials declared the preemptively virtuous right to attack those they define as the Axis of Evil.

Moreover, Lucas is clear about the paths to the dark side: The hunger for more and more power serving a possessiveness and greed that includes surrender to revenge, and to the emotional demands of what Buddhists call attachment. In other words, the current functional morality of our politics and society.

This prequel trilogy says that hot-blooded righteousness in a hero is not enough, for it is too easily turned. Like all cautionary tales, this is a call to consciousness. Like all tragedies, it tells us that even born heroes have human flaws that mirror their society's faults.