You can learn a lot by reading someone's diary. Consider The Reagan Diaries. Anyone who still buys the absurd notion that our 40th president was an "amiable dunce" will be shocked to read the words of a first-rate leader, guiding policy and easily outflanking his political opponents.

To some, including author and historian Lee Edwards, Reagan's grasp of policy is no surprise. Edwards visited the former actor's home in the 1960s and was impressed with his book collection, including many volumes on conservatism. The margins were filled with Reagan's notes.

Listening to some reporters, though, you'd never guess Reagan could even read. "[Reagan and British Prime Minister Margaret Thatcher] quickly formed a bond that overcame their differences of age, gender and -- many whisper -- IQ scores," wrote Washington Post columnist David Broder in 1989. Or as former CBS White House reporter Leslie Stahl put it, "he was a person who didn't understand the issues at all . . ."

The diaries shred that insult. Even those who disagreed with him can't seriously pretend Reagan didn't know the issues. In 1981, Reagan wrote about Thatcher. She "expressed regret that she tried to reduce govt. spending a step at a time & was defeated in each attempt. Said she should have done it our way -- an entire package -- all or nothing," he wrote. Maybe there wasn't such an IQ gap after all.

Reagan also described how he outfoxed congressional liberals. "They want to include a reduction of the inc. tax rate on unearned income from 70 percent to the 50 percent top rate on earned inc. We wanted that in the 1st place but were sure they'd attack us as favoring the rich," he wrote in May 1981. "I'll hail it as a great bipartisan solution."

The diaries also show a president guiding foreign policy. "I told Al H[aig] I had decided to accept his resignation," Reagan wrote in 1982. Why? "The only disagreement was over whether I made policy or the Sec. of State did." So much for the idea that Reagan was a puppet of his advisers.

The key foreign policy issue was the Soviet Union. "We're convinced they want above all to negotiate away our right to seek defensive weapon [sic] against ballistic missiles," Reagan wrote in 1984. "They fear our technology. I believe such a defense could render nuclear weapons obsolete & thus we could rid the world of that threat." After Mikhail Gorbachev became Soviet premier, Reagan met with him several times. "He really wants more reduction of nuclear weapons. I think we'll make progress on the 'Start' Treaty [START, the Strategic Arms Reduction Talks]," Reagan wrote in 1987.

A year later he noted, "Soviets have stopped jamming radio broadcasts such as Radio Liberty & all the others. They have also announced they are releasing 120 pol. prisoners." Seemingly against the odds, the Cold War ended peacefully.

Still, Reagan occasionally failed. In 1983, he requested a meeting with photographer Ansel Adams. "He has expressed hatred for me because of my supposed stand on the environment." Reagan couldn't bring Adams around. "I'm afraid I was talking to ears that refused to hear," he wrote.

When the diaries first came out, reviewers focused on the family squabbles that any parent deals with. But the real story of the diaries is its revelation of Reagan: the inspiring leader, full of big ideas and working hard to make those ideas a reality. To a large extent, he succeeded.

Not bad for an unemployed actor who supposedly "didn't understand the issues at all."

Ed Feulner is president of the Heritage Foundation.