“I won a nickname, ‘the Great Communicator.’ But I never thought it was my style or the words I used that made a difference: It was the content. I wasn’t a great communicator, but I communicated great things.”

–Ronald Reagan in his Farewell Address, Jan. 11, 1989.

The Reagan presidency is now widely regarded as the most successful of the past half-century. How did Reagan manage to be so much more successful than most of his predecessors or followers? Many of the answers can be found in a new book, “Ronald Reagan,” [Westview, 306 pages] by Peter Wallison.

As general counsel of the Treasury in the first Reagan administration, and then as the president’s counsel during the Iran-Contra affair, Peter Wallison was able to observe President Reagan’s strengths and weaknesses firsthand.

Mr. Wallison is a superb writer with the knack of making White House policy and power struggles as gripping as the best who-done-it.

Mr. Reagan was always underestimated by his opponents, and often even his friends. The old “Saturday Night Live” parody of Mr. Reagan where he appeared to be the bumbling, kindly old uncle to the outside world while, in reality, being the dynamic take-charge executive, was much closer to the truth than most people ever knew.

How could a man of supposedly limited knowledge and limited intelligence accomplish so much? How did he get elected and reelected governor of our largest state? How did he get elected and reelected president of the United States? How did he preside over a time of unprecedented prosperity, the winning of the Cold War, and the demise of communism worldwide? How?

“Well, maybe he was a lot smarter than most people thought,” former Secretary of State George Shultz has said.

Ronald Reagan, like Margaret Thatcher, was a conviction politician, someone who actually believed in something, unlike the typical politician with his finger in the wind. As Mr. Wallison explains: “Reagan’s faith in ideas may be unique among modern American presidents. He does not appear to have sought the presidency for its own sake, or for its trappings, or even as the culmination of a lifelong goal. Instead, he sought the presidency to implement a set of firmly held ideas about government’s proper role … . Ironically, in the sense he believed that ideas were more important than individuals or power relationships, Ronald Reagan — no matter how it may gall those who have scorned the quality of his intelligence and called him an actor or a lightweight — was an intellectual.”

Mr. Reagan was the only modern president who researched and wrote by himself more than a thousand commentaries of the public issues of the day. He was thought to be lazy and uninterested in policy yet, in fact, he was a voracious reader of books and policy papers. Of the 670 essays written in his own hand between 1975 and 1979, 27 percent were on foreign and defense policy, 25 percent on economics, 15 percent on government and individual liberty, and 10 percent on energy and the environment.

Mr. Wallison explains how Mr. Reagan’s management style of selecting good people, setting broad policy goals, and then delegating the authority and responsibility to get the task done, resulted in great economic and foreign policy successes. The weakness of the Reagan management system was that, because of the delegation of power, people down the line with poor judgment could make serious mistakes, as in Iran-Contra.

Mr. Wallison was one of those charged with cleaning up the mess and, in fascinating detail, he explains how it happened, and how the president and his top advisers were eventually cleared of wrongdoing but, sadly, how reputations of good people were destroyed in the process.

Mr. Wallison provides detailed evidence to support those who believe that the press is often irresponsible and hostile to conservatives. He describes specific cases of reporters who promised good press coverage to those who leaked unflattering stories, and then unfairly pilloried some who refused to cooperate.

In the case of Iran-Contra, the investigations ultimately showed that the “arms sales were at most a failed and perhaps mistaken policy. There was no cover-up involving the president… Whether there were any clear and established violations of the laws covering the arms sales has never been established, and there were no prosecutions for these matters.” Yet the coverage of what turned out to be a non-crime was clearly excessive.

Mr. Wallison counted 555 Iran-Contra stories in The Washington Post, and 509 stories in the New York Times in the three months between November 1986 and January 1987. In describing the successful but unfair attempt to “get” White House Chief of Staff Don Regan, Mr. Wallison writes: “The fact is they wanted to get him, and they were going to do it no matter who spoke on his behalf. Washington is a very mean town when some formerly powerful person, already in disfavor, is down. It’s like dogs or wolves turning on the deposed leader of the pack to finish him off.” Sound familiar, Sen. Lott?

Those now in the administration ought to keep the Wallison book on their desks as both a reference and reminder of how to make things work and how to avoid mistakes. As Mr. Wallison notes: “In another age, the press might have been interested in publishing and writing about the great issues raised by Reagan’s ideas, and the great debate about the role of government that these ideas provoked. But in an age when the greatest rewards in journalism seemed to go to those who could produce the most sensational stories this was not to be. Nevertheless, because of Reagan’s persistence and conviction, and willingness to pursue his case relentlessly, day after day, during his eight years in office, some of his message got through… a recognition in the United States and around the world that the way to achieve growth and prosperity was through freeing the market from excessive government control.”