It was a splendidly successful demonstration of President Reagan doing what he does best, reinforcing an atmosphere of national optimism and confidence. His State of the Union message spoke of freedom, excellence and progress. Whether you agreed with him or not, you could hardly doubt that he drew most of his audience along with him, not only in the Capitol but around the television sets. It was a happy evening.

He returned to his idea of a second American revolution -- a revolution, it becomes clear, of attitude rather than program. This year's message was a good deal less specific than most of its sort. There were allusions to future legislation, rather than descriptions of it. The message was a celebration of the virtues of liberty and individual initiative, to be expressed in this country through the rule of the market and to be defended abroad by American national power. There are inconsistencies in any president's posture; here the enthusiastic talk of individualism continues while the pace of business growth is being set by a level of federal spending that has gone extremely high by any past standard -- and is currently rising.

Mr. Reagan devoted much attention to tax reform, and he was right to do it. But he has not yet committed himself to a specific plan. There is a Treasury Department proposal, but so far no Reagan proposal. The administration is not quite unanimous about the Treasury's ideas, as the president's Council of Economic Advisers showed in its report earlier this week. If Mr. Reagan wants action on a bill this year, he will have to get it drafted promptly.

Regarding the status of minorities and the equality of citizens' rights, Mr. Reagan continues to believe that additional civil rights legislation can contribute little. What the minorities need, he argued, is "full economic power." Fair enough -- but what is the federal government's responsibility to help them achieve it? Mr. Reagan offered several limited suggestions, beginning with enterprise zones -- an idea he advanced in his State of the Union address three years ago. That year the enterprise- zone legislation came to a vote in neither house of Congress, for solid reasons that Mr. Reagan did not take up in this week's repetition.

There was less about foreign policy in this year's message than is usual on these occasions. The president spoke of his commitment to pursue the nuclear arms negotiations and of the national responsibility to advance freedom throughout the world. He invited this country's allies to join it in a "practical program of trade and assistance" for the Third World. But his budget, published Monday, hints at reductions in American support for the international development banks through which that aid is now being delivered most effectively.

It was a speech for a serene moment in American history -- a time when things are going well, prosperity is high and no great new challenge or threat is visible abroad. Mr. Reagan spoke to the country's mood. If he proposed no great changes in the government of the country, it was because most of his audience see a need for none.