Even given the daily excesses of this Media Age, the circumstances and the staging of Ronald Reagan's triumphant homecoming from the summit were extraordinary. They had all the elements of a public play similar to an ancient supplicatio, or sustained period of thanksgiving, declared by the people of Rome after Caesar won some great victory in far-off Gaul. Like mighty Caesar, we saw that Reagan's legion of admirers was exultant, his erstwhile critics could not wait to shower petals in his path, his standing among the populace soared even higher. The Democratic minority leader of the Senate, Robert C. Byrd, for one, told his fellow countrymen over television that he slept better now that the president had achieved such a happy ending to his exercise in personal summit diplomacy.

Come to think of it, a better analogy for this latest Reagan political performance could be drawn from one of the president's favorite authors, the western writer Louis L'Amour.

Being celebrated was the good sheriff, weary but unbowed, standing tall and modestly accepting acclaim from the cheering throngs after doing battle with an implacable adversary -- all, it seemed, with the help of the networks. Even the subtitles filtering over our TV screens evoked a L'Amour western saga of good and evil: "Reagan's Return" read the words superimposed on the screen by NBC. Rawhide was back. And all this as the president's helicopter, red light flashing, was shown winking its way through the night toward the Capitol, circling the familiar monuments bathed in soft yellow lights and forming perfect presidential props, and then touching down for the great reception at the Capitol.

That all this stage-setting was overdone, and that the summit achievement, however defined, was quite limited, in no way detracts from what Reagan did accomplish -- or the opportunity that now is his.

His speech to Congress was, in the view here, the finest of his presidency. Not because it was his most eloquent, or delivered most effectively, or contained the most memorable lines of the speechwriter's art. It was none of these. In fact, at one point, Reagan, the political master of the TelePrompTer, stumbled quite badly and uncharacteristically, creating an expectant hush, a collective holding of breath by the assembled members of Congress, until he regained his place and completed quoting what Ike had said nearly 30 years ago after an earlier Geneva summit.

Reagan's speech was impressive because of his tone. Throughout, he was dignified and statesmanlike as he reported simply and convincingly on what had taken place in Geneva and related how much remained to be done. He was entirely realistic and, probably most important for the future, conciliatory and generous toward the Soviets. He made no false claims for historic breakthroughs; he did not promise, as he does so often, the inevitable happy ending; he did not minimize the difficulties and the differences that divide the United States and the Soviet Union; but neither did he attempt to make cheap ideological capital, for home political consumption, of the evils and dangers inherent in "the communists."

In this appearance, Reagan made you feel he truly believes in starting fresh with the Soviets -- and that he wishes to leave as a legacy a sounder relationship bringing with it the prospects for a more peaceful world. He was refreshingly free of his former harsh rhetoric and bitter hostility toward the Soviets. He deserves to be applauded.

One speech does not a future make, of course, nor does one meeting between feuding heads of state a resolution of previous problem guarantee. And within his words, I thought, were signals of some trouble ahead. These took two forms.

First, Reagan obviously still clings to what he properly calls his "dream" about "Star Wars" with its wondrous umbrella shield that protects all without hurting anyone else. It is an intoxicating theory. Instead of a defense against nuclear holocaust based on the concept of mutual destruction, presto, here we offer the ultimate fail-safe and painless system: simply put a laser shield in space that will prevent any nuclear weapons from falling on us. This flies in the face of scientific perfectibility. Adherence to it makes genuine arms reduction more difficult and true mutual arms control efforts with the Soviets almost impossible.

Second, Reagan strongly hinted that he expects Congress to give him more -- not less -- funds for defense as the lawmakers deliberate about how to resolve the deadly budget deficit dilemma before them. He's most unlikely to be granted this wish. If he pushes them too hard in this direction, he stands in danger of destroying the good will that now surrounds him. He could lose on both the defense increases and the domestic spending cuts he desires.

Yet despite these concerns, another intriguing possibility arises out of this current high moment in Reagan's presidency: that he today stands in a position to achieve not only success abroad but also at home.

He has made possible a breakthrough in foreign policy by easing his previous rigidity toward the Soviets and seeking to a set a more positive climate. He has the same opportunity to take the lead on the domestic front to break the budget impasse by easing his previous rigid stance. Let him call a domestic summit of leaders of Congress, signal his willingness to accept cuts in both defense and entitlements and agree to tax increases if necessary. The deficit would then surely decline. All Americans would be the beneficiary. His political standing would soar even higher. If he does this, he could go down as a president who led his nation into a more peaceful and prosperous period.

Now that would be a historical record of success on foreign and domestic fronts truly worthy of the acclaim accorded a Caesar.