Last week, the foundations of a hamlet were found near Stonehenge, the puzzling Neolithic monument near Salisbury, England. Archaeologists hope the new evidence may help determine how and why the cluster of vast stones was erected. The discovery has come as a surprise. For all the centuries of speculation surrounding the famous henge, few imagined that just below ground were artifacts, buried for 2,500 years, that would yield valuable clues.

The same is true of the life of Ronald Reagan. So much has already been written about a man who thrust himself into the public spotlight in his teenage years and remained there the whole of his life that it was thought that all that was left for Reagan scholars was to sift through and reinterpret the old material.

Now Thomas W. Evans, an American lawyer who has dabbled in Republican politics, has made a genuine breakthrough in “The Education of Ronald Reagan” (Columbia, 302 pages, $29.50) by uncovering the influence upon Reagan’s political thinking of Lemuel Ricketts Boulware, the General Electric executive who employed Reagan when acting work dried up in Hollywood. Neither Lou Cannon, in his magisterial life of Reagan, nor Edmund Morris, Reagan’s official biographer, make mention of Boulware, yet Mr. Evans makes a strong case that Reagan would not have made the leap from Democrat to Republican in 1960 had it not been for Boulware’s proselytizing of free markets and low taxes.

Until now it has been assumed that Reagan was the source of his own conversion. He was born into a Democratic family, his father was active in New Deal good works on behalf of the unemployed, and he remained a liberal in Hollywood. By his own account, he made the slow journey from left to right through personal experience. During the Depression he noticed that federal bureaucrats were often more devoted to maintaining their own jobs than finding work for others, and when he began making a movie star salary he begrudged the confiscatory taxes he was obliged to pay. Above all, as president of the Screen Actors’ Guild, he found himself in fear of his life as he battled communists in the movie industry. Like Margaret Thatcher, Reagan found his political philosophy not through reading dusty tomes of political philosophy but by following his own instincts.

Mr. Evans does not dispute this account, but by sifting through the GE archives at Schenectady and Boulware’s papers at the University of Pennsylvania he has unearthed a seam of influence on Reagan’s thinking which no one else has mined. He makes a convincing case that in his years traveling as the public face of GE to its 135 factories, where he addressed hundreds of thousands on the shop floor, Reagan imbibed the wisdom of Boulware’s promarket, anti-trade union, conservative thinking, which ran through the company’s voluminous literature aimed at keeping employees safe from creeping socialism.

Reagan was already much in demand as a speaker, preaching the virtues of small government and low taxes. He had formulated an all purpose address, “The Speech,” which laced homespun conservatism with telling anecdotes and which was to become the instrument by which he propelled himself onto the national stage in his rousing television appeal in support of Barry Goldwater’s failed presidential bid. Reagan seemed unaware he was being employed to do anything other than keep GE employees content by offering them tidbits of gossip about their screen heroes. It was, perhaps, the genius of Boulware that Reagan was allowed to feel that he was sneaking politics into the mix.

But mysteries about Boulware’s influence remain. When Reagan’s political career took off, Boulware and his boss, Ralph Cordiner, were keen supporters and kept in touch with him, though neither was admitted to the “kitchen cabinet” of multi-millionaires who fostered and bankrolled Reagan’s political ambitions. Nor, when Reagan entered the White House, did “The Gipper” give credit to Boulware for the “education” he received from the executive known throughout GE as “The Great Communicator.”

You will not find mention of Boulware in John Patrick Diggins’s “Ronald Reagan,” (Norton, 464 pages, $27.95) though there are plenty of references to Max Weber, Tom Paine, Karl Marx, and other important political theorists. There is little evidence that Reagan’s political philosophy was directly inspired by anything he read in a book. He sensed that lower taxes caused people to work less hard decades before Arthur Laffer drew his curve on a napkin. And he watched his father’s unemployed friends shrivel in the face of New Deal welfare programs without recourse to Ayn Rand. Although grateful for the support of intellectuals, Reagan was never caught brushing up his Milton Friedman. Reagan’s success was founded on the ragbag of ideas which he attributed to “common sense.”

One of the paradoxes of the revolution in attitudes Reagan set in train is that while he dominated the national dialogue for eight years and nudged the nation politically to the right, socially and culturally the country continued moving inexorably in the direction set by the 1960s. Robert M. Collins’s “Transforming America: Politics and Culture in the Reagan Years” (Columbia, 350 pages, $29) is an astute account of politics and culture during the Reagan years, yet he is at a loss to explain why the powerful movements of conservatism and reaction unleashed by Reagan’s electoral success failed to stem the progressive tide.

Which is not to diminish Mr. Collin’s achievement. He displays acute understanding of Reagan’s contributions to such mammoth events as the ending of the Cold War, the move from Keynsian economics, and the restoration of America’s self-confidence.

The answer to the conundrum may lie in Reagan’s age – too old to understand the excitement felt by those liberated by the 60s – and his oft described insularity which set him apart from everything and everyone, including his wives and children, leaving him, perhaps, oblivious to feelings and movements he did not himself experience and therefore incapable of engaging in their arguments.

Mr. Wapshott, a biographer of Margaret Thatcher, is writing a joint life of Reagan and Thatcher.