WHEN RONALD Reagan said that it was "morning in America," people listened. The most popular and successful politician since Franklin Roosevelt, Reagan could do little wrong in the eyes of the American public. And when he did, few bothered to hold a grudge. But like an Arctic landscape after six months of sunlit summer, the American political picture has suddenly grown dark.

Ronald Reagan is no longer the apple of our eye--or the sunshine of our life. Even his friends feel betrayed. "He will never again be the Reagan that he was before the blew it," Republican Representative Newt Gingrich of Georgia, one of the President's staunchest allies in the Congress, said the other day. "He is not going to regain our trust and faith easily."

Reagan's America: Innocents at Home

By Garry Wills

Doubleday; 472 pp.; $19.95.

How did Reagan gain our trust and faith so easily in the first place? And just who and what was the Reagan that "Reagan was before he blew it"? Fortunately, Garry Wills, one of the most perceptive social critics of the last two decades, has spent several years searching for answers. The result is the recently published Reagan's America: Innocents at Home, an impressive effort to understand Ronald Reagan and America's fascination with him.

WILLS DEFINES Reagan's appeal the same way Roland Barthes defined myth: "He is a durable daylight `bundle of meanings,"' Wills writes. "Reagan does not argue for American values; he embodies them." Gifted with his salesman father's Irish blarney and his sermonizing mother's penchant for moral crusading, Reagan articulates and seems to embody values Americans prize most. He can josh with an audience and then preach to them. Self-deprecating, humble, unpretentious, charming and--most importantly--a financial and social success, Reagan stands as the "fulfillment of America's ideal--Everyman suddenly put in charge of the nation's destiny, the good-hearted non-professional with `common-sense."'

Like America itself, though, Reagan is full of contradictions and oblivious to most of them. Wills dissects Reagan's early life and catalogues Reagan's historical revisions and inventions. Reagan would have it, for instance, that his family struggled through the Depression on its own. Yet Reagan and his brother were both able to attend college during the early 1930's. How so? Reagan's father, a loyal Democrat, used party connections to secure an important job with a New Deal public works agency. The New Deal, it turns out, "bailed the Reagans out."

Wills also collects some of the more telling anecdotes Reagan has told through the years. One of Reagan's favorite tales involves the crew of a B-17 hit during World War II. After the crew bailed out, as Reagan tells it, the pilot turned to a gunner too wounded to move. The gunner implored the pilot to save himself but to no avail. "Never mind, son," the pilot says. "We'll ride it down together." Reagan tells this story to exemplify the difference between Americans and Russians. Okay. But if the two pilots were alone in the plane and went down together, how does anyone know their final words to one another?

IT DOESN'T matter, Wills argues, whether the flyers' conversation ever took place or a high school football game Reagan often draws a moral lesson from was ever played. (It wasn't.) For Reagan, the moral lesson comes first; it shapes the event, not the other way around. Perhaps Wills' most important insight into America's 40th President can be found in his discussion of Reagan's days as a sports announcer. Reagan's detractors, who dismiss the president as "just an actor" and view him as no more than a tele-prompted automaton, have not looked back far enough into his past. If they did, they would better understand the man and his appeal.

Before Ronald Reagan achieved fame as a movie star in Hollywood, Dutch Reagan was an enormously popular baseball announcer and newspaper columnist in Des Moines, Iowa. Iowans followed the fortunes of the Chicago Cubs, and Dutch was their favorite play-by-play man. Yet Reagan had never seen a big-league ball game when he began broadcasting them and still hadn't after four years on the air.

Reagan described the games from a room in Des Moines. An accomplice with a wire set hooked up to Wrigley Field handed him slips of paper after each pitch: "double," "strike, inside corner," "foul ball". It was Reagan's job--and particle of talent--to fill in the rest. Then, later that night, listeners tuned into Reagan's analysis of the day's events--events he had created in his own mind.

Reagan was reknowned for his ability to "visualize" games and--from scraps of paper--invent an absorbing world of heroic athletes. Listeners knew he was inventing the games, but pretended otherwise. It was more exciting that way. "There was a complicity in the make-believe," Wills writes. And why not? After all, a ball game had taken place, one team had won, and such-and-such a player had hit a home run while another struck-out.

Reagan created a mythic world in the afternoon and gave it moral dimension at night. He wasn't so much describing reality as making a point. That is pretty much what he has been doing ever since. He denies that Hollywood marriages can't last as he is being divorced from Jane Wyman. He tells of acting triumphs in scenes never filmed. He brags he spent less as governor of California than either Brown after outspending both.

He claims to be a "rabid union-man" after betraying his fellow actors while president of the Screen Actors Guild and busting the air-traffic controllers union when president of the United States. He tells Israeli and Jewish leaders he filmed death camps at the end of World War II "so I'd never forget," yet he spent the war at home. No matter that many of his stories are false and others distant memories of movies seen long ago: He's just making a point. And Americans, who twice have elected him President, are complicit in the make believe.