Ronald Reagan is our Prince Hal. No less than Shakespeare's ebullient Prince, he "imitates the sun."

Few presidents in American history have been better at playing such a cheering public role, or more naturally suited to it. In this century, only the two Roosevelts matched his innate ability to transform personal adversity into political assets. Theodore, when shot in the chest while delivering a speech, continued with his address, then told his fellow citizens he felt "fit as a bull moose." Franklin, at all points in his long presidency, maintained so sunny a demeanor that most Americans never thought of him as totally crippled. Millions, it seems, never even knew he was paralyzed from the waist down and confined to a wheelchair.

In today's infinitely more cynical society, where small children are aware of the artifices and deceits of the PR and ad merchants that surround them via their TV screens, there has been a disposition among Reagan's critics to disparage his continual cheery appearances. It is all, they say, just part of his actor's training. It's all a charade.

Surely there has been a method in his constant waving and smiling at us, his fellow citizens, through the lens of the all-seeing TV cameras that follow his every public move.

He waves at us when no one stands before him on the White House lawn other than camera crews and security details. He waves at us when surrounded only by bodyguards inside his Oval Office. He waves at us when stepping from a helicopter at some remote site off-limits to the public.

There is no mistaking the calculation behind the latest beaming pictures of the president: laughing, waving, flashing the thumbs-up and A-Okay signs from his hospital room, from the helicopter steps as he headed home yesterday a week after surgery, and from the White House balcony to a welcoming crowd on the South Lawn.

He and his wife, who poses with him to wave and smile for the cameras and thus to us, are performing an ancient ritual of leadership. They are reassuring the people no less than does a pope from the balcony of St. Peter's, or a king and queen from the balcony of Buckingham Palace.

The deliberate device of employing the "photo opportunity," raised from political tool to art form during the Reagan presidency, in no way diminishes the reality of Reagan's performance.

Twice now, he has displayed remarkable traits in responding to the threat of death.

His impromptu remarks while he lay wounded from a bullet in the chest were not artifice. No script writers crafted those lines for this president. His "Honey, I forgot to duck," (an old Jack Dempsey line, uttered in the boxing ring after Dempsey lost his heavyweight crown to Gene Tunney in the late 1920s), and his "I hope you fellows are Republicans" to his doctors while bleeding from his wound, came forth spontaneously from the real man.

Those were unmistakably genuine. They endeared him to Americans who instinctively recognized in them behavior they like to believe exemplifies the best in the American character -- courage in adversity and a breezy spirit of optimism in the face of imminent disaster.

Now, in his response to major cancer surgery, he has given the country another demonstration of gallantry and courage. If for nothing else, he will be remembered for these personal responses to tragedy long after the record of his administration has been forgotten. He seems certain to join the handful of presidents who are held in true affection by the people.

In this latest crisis, two questions now confront Reagan and the country. There are no easy answers to them, for they are without precedent in the American experience. Both are highly intangible, but nonetheless critical.

The first involves how Reagan will react to the fact that he, as his doctor told the world over TV last Monday, "has cancer" -- and is recuperating from major cancer surgery where the odds are only 50-50 that he will be cured. The second involves how the public will respond to that knowledge.

Americans, in the last generation, have learned to deal with difficulties and tragedies besetting their presidents. They witnessed one, John F. Kennedy, murdered. They saw another, Richard M. Nixon, destroyed and disgraced. They watched two more, Dwight D. Eisenhower and Lyndon B. Johnson, hospitalized and recover from major surgery. But never have they experienced the knowledge that their president has had -- and may still have -- a disease they so fear and dread.

Nor has a president ever had to perform his public duties with such personal knowledge, and under such inevitable public scrutiny and speculation as are bound to be the lot of Ronald Reagan in his final years in the White House.

The fact -- the historic fact -- is that no one can say how any of this will turn out, or how we and he might react to potential bad news. I do not raise this prospect out of morbid speculation or to dwell on what critics of the press always accuse us of, and often properly so: our penchant for accentuating the negative. The hope is that this story, for this Prince Hal of a president, has a sunny ending.

In that respect, the words last week of Irving Rimer of the American Cancer Society are worth citing:

"As far as the ability of the public to take the president's illness in stride," he said, "that will be determined by his behavior. He has already begun to show that he has returned to normal behavior: walking within 24 hours of surgery, the general way he came out of surgery, his talk of going to the ranch, riding horses and chopping wood.

"Since Ronald Reagan is such a well-loved individual, he will be closely watched by the public and all of his actions and reactions noted. Behavior such as that which he has already begun to exhibit will aid the public in seeing that cancer is not the dreaded, always-fatal monster that it appears to many to be. It does not have to be debilitating; when caught early, in time, one can return to a normal life."