EVANSTON, Ill. - Like the conductor of his own chamber orchestra, Garry Wills presides over three metal music stands while at work in his study, his chosen "scores" including dictionaries of Greek, Latin and Italian.

He might need, for example, to look up the Greek word "ekklesia," which appears in the New Testament and is commonly translated as "church." A mistake, Wills says. "Ekklesia" means "gathering," an informal assembly. "Church" implies a Christian hierarchy that never existed in biblical times.

"As Mark Twain liked to say, the difference between the right word and the almost right word is like the difference between `lightning' and `lightning bug,'" Wills explains.

Author of more than 30 books, along with countless essays and reviews, Wills is a classicist who has made an art out of correction, whether a word, a theory or a historical event. He has explored -- and made many reconsider -- the origins of Catholicism, the confessions of Saint Augustine and the influences on the Declaration of Independence.

Once praised by critic John Leonard for reading like a combination of "H.L. Mencken, John Locke and Albert Camus," Wills has been popular and prolific in recent years. Since 2005, he has completed a full-length book on Henry Adams, short works on Jesus and Paul, and a full-length history of religion in the United States, "Head and Heart." He has already completed a book on the Gospels, coming out in the spring, and has started a history on the "divided legacy" of the military and American culture.

"He is the American man of letters, par excellence," says prize-winning historian Edmund S. Morgan, whose many books include "American Slavery, American Freedom" and a best-selling biography of Benjamin Franklin.

"He has an enormous intellectual curiosity, which I regard as the greatest attribute any scholar could have, so that his curiosity takes him in many different directions, often with very important results."

Wills is 73, with large, squarish glasses and a face to match. For the past quarter century, he and his wife, Natalie, have lived in a 1920s brick house, where on the walls you will find a montage of cardboard cutouts of John Wayne films, a caricature of British author and (fellow Catholic) G.K. Chesterton or a framed copy of the Gettysburg Address.

He was a thinker early on, even when life seemed unsuited for it. A native of Atlanta, Wills was born in 1934, when his parents were still in high school, and he moved throughout the Midwest as his father looked for work, at times going door to door to sell the bread Wills' grandmother baked. The family eventually settled in Adrian, Mich., and Wills ended up thriving in Catholic schools, including "a high school where we were taught by young students, people halfway through their training as Jesuits. They were in their 20s and were still full of enthusiasm."

He has childhood memories of "falling in love with Dickens, with opera, with Shakespeare," and was encouraged to write. In the mid-1950s, he gained an important admirer, William F. Buckley, Jr., founder of the National Review, the conservative magazine.

Wills, then a student at Xavier University in Cincinnati, had submitted a parody of Time magazine. Soon after, he was in his dorm room when a fellow student told him he had a call on the house phone: It was Buckley, urging him to come to New York and "talk to us." Wills became the Review's drama critic, and a friend and protege of Buckley's, a frequent sailing partner who jokes that he had to cut back on his leisure time with Buckley for fear that it would interfere with his job.

Meanwhile, the learned young man was becoming one of millions changed forever by the 1960s. Wills describes himself as a "Catholic anti-communist" in his youth, shaped in part by the prayers at his church that called for the conversion of the Soviet Union. But he found himself increasingly sympathetic to the Vietnam War protesters and civil rights marchers regularly opposed by Buckley and friends.

"Bill's attitude was, `If we criticize ourselves on our racial policies, then we're playing into the hands of the enemy,' so we just have to say everything's hunky-dory," recalls Wills, who eventually reconciled with Buckley after a long estrangement.

"They thought of the Vietnam War as an anti-communist war and by that time (the late 1960s), it wasn't. ... Finally, I sent him a piece arguing that the Vietnam War was ... hurting the country and not the Communist cause. And he said, `I can't run that. It would anger too many people.'"

By 1970, the break was final. Two years earlier, writing for Esquire, Wills had covered then-presidential candidate Richard Nixon. He expanded his reporting into "Nixon Agonistes," which infuriated conservatives with its dissection of Nixon ("He lacks the stamp of place or personality"), even as liberals complained that the author had been too kind.

"`Nixon Agonistes' is still an important and fascinating book" even though it was written before the Watergate scandal and incorrectly predicted the demise of self-made men such as Nixon, says historian David Greenberg, author of "Nixon's Shadow: The History of an Image."

Greenberg, who teaches history and media studies at Rutgers University, praised "the acuity of Wills' analysis and his ability to locate Nixon in the intellectual climate of his day." He also called the writing "virtuosic -- a blend of fairly dense academic analysis with magazine-feature color."

Wills continued calling himself a conservative into the late 1970s, even titling one book "Confessions of a Conservative," but that word, no matter its meaning, no longer applies. Wills is dependably liberal on most issues, even radical, in the Latin sense of the word, for someone who gets at the "root" of a subject, digging through the layers of error.

In book after book, he probes and provokes. In "A Necessary Evil," he questions the American bias against "experts," noting, for example, that the citizen militias of the Revolutionary War were almost completely ineffective. "Lincoln at Gettysburg," winner of the Pulitzer Prize in 1993, argues that Lincoln's most famous speech has been misread as casual remarks pulled out of his stovepipe hat.

Wills is most persistent on the subject he feels most profoundly: religion. He is a Catholic so unhappy with the church that he wrote "Papal Sin," a best seller called "sorely offensive" by the Catholic League. He is so versed in the Bible that he needed little time to complete his recent series of religious works, including "What Jesus Meant" and "What Paul Meant," which contend that the egalitarian teachings of the scriptures had been transformed into justifications for those in power.

"He's a Catholic controversialist, a real Catholic who is not afraid to take on people (all the way up to the Pope) who he feels traduce elements of it, or exploit it," says religious scholar Martin Marty, known for his five-volume "The Fundamentalist Project" and for "Righteous Empire," winner of the National Book Award in 1970.

"Some Catholics are critical of critic Wills, but I find him to be incurably Catholic in sensibility, outlook, and loyalty."

Religion works best, Wills says, when separated from government. In the introduction to his current book, "Head and Heart," he recalls a conversation with the Dalai Lama, whom he interviewed before an audience at Chicago's Field Museum. Encouraged by the Dalai Lama to "Please ask hard questions," Wills wondered what he would do differently if he were returned to power in Tibet.

"I would disestablish the religion," the Dalai Lama replied. "The American system is the right one."

Wills writes that neither the founders nor the population as a whole were especially religious in the country's revolutionary years. He counters beliefs that the evangelical fury of Jonathan Edwards and other Puritans influenced the founders and calls the American Revolution a triumph of the Enlightenment, of reason and inquiry.

His next project is a study of the military in American culture. Again, some clarification is needed, such as the very meaning of calling the president "Commander in Chief," an inversion of Walt Whitman's boast that we live in a country where leaders tip their hats to the people and not the other way around.

Wills doesn't cite Whitman, or the Bible or a dictionary, but the Constitution, Article II, Section 2:

"The President shall be Commander in Chief of the Army and Navy of the United States, and of the Militia of the several States, when called into the actual Service of the United States."

He is commander only of the "Army and Navy" and "of the Militia," Wills notes, not everybody's commander. And yet even civilians feel pressured to salute the president and "you're not a true American if you feel otherwise.

"The whole cult of the president as Commander in Chief is quite unhealthy."

Like mistaking lightning for a lightning bug.