Ronald Reagan's hero is Franklin D. Roosevelt. But his prototype is Georges Boulanger, the original man on horseback. An immensely popular and dashing general, Boulanger in 1889 was cheered by Parisian crowds which exhorted him to lead a putsch against the French government. Instead, he had second thoughts and fled Paris. The man on horseback had feet of clay.

Reagan, in the discrepancy between promise and performance, is our Boulanger. Handsome and charming, he is every inch the president. He wears his clothes well. He crisply and frequently salutes as no commander-in-chief has ever done. He is the master of the macho quip: ''Make my day,'' he says to terrorists. On television, he looks his country square in the eye. Ronald Reagan has been the personification of strength and leadership.

But the picture of Reagan that has emerged from both the Tower Commission report and the congressional hearings into the Iran-contra affair is fundamentally at odds with the one we get on television. The extraordinary testimony of Adm. John Poindexter and the despairing testimony of Secretary of State George Shultz show a weak Reagan who was the captive of his aides. Like some underage monarch, he was dominated by his court -- uninformed, misinformed, and distant, living in a West Wing of his own hazy imagination. Not even an urgent call from the secretary of state could get through.

By almost any measure, the attempt to sell arms to Iran in exchange for the freeing of American hostages was a perilous undertaking. First, it contradicted Reagan's stated policy that the United States would never bargain for the lives of hostages. Second, Reagan and his aides knew well that the hostage issue proved instrumental in the fall of Jimmy Carter. And, third, Iran is both critical to U.S. interests and ruled by an unpredictable madman. The boys in the White House basement were playing with matches.

Yet, Reagan cavalierly approved the arms-for-hostages deal while remaining almost completely uninterested in its potential hazards. Shultz related how, before the president's Nov. 19, 1986, press conference, he went to Reagan to say, ''We've been deceived and lied to. You have to watch out about saying no arms for hostages.'' To this, according to Shultz, the president replied, ''You're telling me things that I don't know, that are news to me.'' Even so, Reagan memorized his script and denied the facts to the public: Arms had been traded for hostages and Israel had a role in the endeavor.

To some defenders of the president, the Iran-contra affair raises grave questions about Congress and its insistence that it share in forming foreign policy. In fact, Poindexter and Oliver North maintain it was the inconstancy of Congress when it came to contra aid and its tendency to leak classified information that prompted them to work in dark secrecy. Congress, they argue, is weak; Reagan is strong.

But by manipulating television, the White House manufactured a president who, in reality, did not exist. Reagan, a former actor, proved that playing president was his greatest role. Congress, however, knew all along his pose for what it was. On the Hill, the president was admired -- even feared -- for his political skills, but there was always an undercurrent of contempt, too. He was known to be lazy, an inattentive delegator -- a man insufficient to his office. In yet another internal government fight -- the battle for what the public would believe about Reagan -- the White House easily prevailed.

Now, it seems, the senior National Security Council staff and the secretary of state shared that view of the president. Men who publicly wrapped themselves in the glad rags of presidential loyalty privately regarded Reagan with contempt. Their testimony reveals a president manipulated by his staff, kept in the dark about his most important policy decisions. They knew he would recite at a press conference what was written out for him. They fought for his attention and support only to gain his approval for their actions, not his understanding. Once they got his imprimatur, they could -- and did -- do pretty much what they wanted. In the Reagan White House, they were on their own.

The Iran-contra affair does indeed raise difficult questions about how a divided government makes united policy. But it also raises profound questions about a White House in the television age that has mounted a president on a horse and presented him as something he is not.

The image of strength and leadership that Reagan presented was restricted to airtime. In reality, this man on horseback was being led down the bridle path.