During the 2000 election, Republican smear artists trying to stop the presidential campaign of John McCain spread rumors that the former POW was "nuts" because he had been "in the cage too long"—in the Hanoi Hilton for five and a half years. The campaign decided to make public Captain (now Senator) McCain's medical records, which showed that he had an enlarged prostate and trouble lifting his arms (repeatedly broken in captivity), but had been judged perfectly sane by a series of Navy psychiatrists who had tested him for years after his release from prison.

The details of those medical evaluations make you wonder why McCain is not stark raving mad today. Tortured repeatedly to extract a confession, McCain "tried to hang himself X2 to avoid giving in," reads the report of a psychiatrist at Jacksonville Naval Hospital in Florida who had interviewed McCain in 1973. "Broke three teeth as a result of rocks in diet," records another. Last week, as I read to McCain from these long-ago documents, he chimed in, "And also a fist in the face a couple of times." McCain was relaxing in a luxurious suite at the Beverly Hilton hotel in Los Angeles, having just received the endorsement of Gov. Arnold Schwarzenegger (the two made an odd couple—the tanned, coifed, buff movie warrior and the pale, wispy-haired real one). His years in captivity were "terrible," McCain said, but, his voice gaining emphasis and urgency, he went on: "In some ways, it was the most magnificent time, because of the courage and bravery of those I had the privilege of serving with." He seemed to hear himself and quickly added: "Veterans really hate war. I hope there's no glorification of war in anything I've written or said."

But there is. How could he avoid glorifying war in a memoir called "Faith of My Fathers" about his grandfather, who commanded a carrier fleet against Japan in World War II, and his father, who was an ace sub commander in World War II and commander of Pacific forces in the Vietnam War? What he objects to, he later made clear in the interview with NEWSWEEK, is "self-glory." The lesson from war he learned—the true faith of his fathers—is that there are "causes greater than self," like country and freedom, worth dying for.

The McCains are not like most Americans. They belong to a warrior caste that has been fighting America's conflicts for more than two centuries. (McCain's grandfather Adm. John S. McCain was depressed at the surrender of Japan. He complained to his chief of staff, "I feel lost. I don't know what to do," and died of a heart attack four days later.) The legacy and experience of war in some ways made John S. McCain III a truly humble man, capable of profound forgiveness—even for the jailers who abused him in Hanoi. But McCain's grace was hard won, and it is in a way a work in progress, a one-day-at-a-time struggle and balancing act. He is often funny, even devil-may-care, and at the same time a little sad. His temper lurks—controlled, but sometimes barely. I asked about a report that McCain's handlers need to caution him against blowing up during presidential debates. "No," he said. "They told me to appear presidential." McCain flashes a smile from time to time that is more like a smirk, "a defense mechanism—to smile, not appear angry or frustrated," he acknowledges. "I had to smile a lot last night," he adds, trying not to smirk. In a debate, his chief opponent, Mitt Romney, had tried to get his goat by raising doubts about McCain's conservative credentials and by accusing him of distorting his record.

McCain, who clearly cannot stand Romney (and vice versa), bridles at anyone or anything that impugns his honor, most sacred of military virtues. In rare weak moments, he can seem prickly, impetuous, vindictive—the sort of military martinet whose finger is supposed to be kept far from the button. Yet he is endowed with self-knowledge and self-effacing dignity. "I'm a man of many failings," McCain says with a genuine, if practiced, ruefulness. "I make no bones about it. That's why I'm such a believer in redemption. I've done many, many things wrong in my life. The key is to try to improve." There are a number of U.S. senators who can attest to McCain's repentance with handwritten apologies for his intemperance.

John McCain, 71, will be the oldest president ever elected if he goes on to win his party's nomination and the White House in November. He has made a long, hard journey from being a "rebel without a cause," as he described himself to one of those Navy psychiatrists back in the 1970s, to a man who aspires to lead the nation and the world. As an angry toddler, he would hold his breath until he passed out (his parents' cure was to drop him fully clothed into a bathtub of icy water). He has found transcendence, if not exactly peace, through duty and suffering that most people can barely imagine.