It is a disturbing experience to watch your own brother, your flesh and blood, dabble in the occult, become consumed by ambition and then descend by stages into murder. And the last straw was when he ordered the slaughter of those children.

But it was even harder for my younger brother Christopher to play Macbeth 13 times at the Great River Shakespeare Festival in Winona, Minn., giving sympathetic life to a moral monster, under seven layers of Scottish armor while carrying a 20-pound spear. It is a tribute to his skill that when Macbeth's head was finally brought on stage in a bloody sack, it did not feel like justice done but like the departure of the play's vital, lawless center.

Every summer, the church of Shakespeare holds services called festivals in Alabama, Hawaii, Lake Tahoe, Hampton Roads and nearly every place with cultural ambitions. There is Shakespeare by the Sea in Redondo Beach, Calif., Shakespeare on the Green in Wilmington, N.C., Shakespeare on the Sound in Norwalk, Conn., and Shakespeare Under the Stars in Wimberley, Tex. And the worshipers are fervent and knowledgeable; an actor at the Winona festival was distracted one night by an older woman in the second row who mouthed the entire play along with the production.

Some of this attraction is the beauty and complexity of Shakespeare's words -- the tumble of ideas and images that yield more meaning on the 10th hearing than on the first. But the amazing achievement of the plays, as critic Harold Bloom and others point out, is when characters such as Hamlet, King Lear or Macbeth transcend the words they speak and come to life -- transformed into what the poet Shelley called "forms more real than living man." Other playwrights use characters as mouthpieces for their own wit or philosophy. Shakespeare's greatest characters seem to possess the spark of their own identity. They have somehow escaped the cage of the author's intentions.

These fictional but living characters have influenced politics and history. Abraham Lincoln was obsessed by Shakespeare's histories and tragedies, once writing, "I think nothing equals 'Macbeth.' " There is something eerie about his brooding on the examples of leaders driven by ambition, cursed by fate and destined for a violent end. After visiting a fallen Richmond in 1865, on his river trip back to Washington, Lincoln read aloud a passage from "Macbeth" about Duncan's assassination: "Treason has done his worst; nor steel, nor poison / Malice domestic, foreign levy, nothing / Can touch him further." Moved by the words, he read them over again.

Not long ago, according to historian Michael Beschloss, archivists discovered a high school essay written by a 16-year-old Harry Truman on "The Merchant of Venice." As a student in Miss Brown's English class, Truman argued that after 2,000 years, the Jews were "a nation apart from nations . . . persecuted for their religion" and still "waiting for a leader" to gather their "scattered people." Many decades later, President Truman took a grave and controversial risk by recognizing the state of Israel -- an issue he had first considered as a teenager at Independence High School reading William Shakespeare.

Yet Shakespeare's influence is not primarily ideological or even religious; his views on these topics are cloaked and obscure. He does not attempt to explain history or the gods to men but rather to explain men and women to themselves. His narrow topic is humanity, and it is immense: everything from stalking guilt to bawdy humor, from insanity to jokes about passing gas, from love to death to those moments when they are inseparable.

In a time deluged by ideology -- when everyone is urged to take a side and join the political battle -- Shakespeare offers a different message: that the most important and dramatic choices are made in the human soul. Some steps, once taken, cannot be retraced. Some appetites, once freed, become a prison.

But the plays are not simple sermons. Fate can be indifferent to our best intentions. Even the purest love can lead to disaster. All our explanations of suffering are incomplete.

We watch the struggling souls in Shakespeare's plays with uncomfortable self-recognition. In their raw honesty we see our own nature, even those parts that are despairing and lawless. And as these characters are transformed, we see ourselves differently as well.

And so we enter a dark theater (or green or beach or riverside) and escape to what is most real.