Whatever else he does during his administration, at least President Reagan won't be wasting time learning how to look good on television. He doesn't have to look any better on television than he did Thursday night. It may not be possible to look any better on television than he already does.

In his economic address to the nation, President Reagan proved, again, a brilliantly relaxed and instinctive television performer and one who, through years of practice on the silver screen (and on the little gray screen, too) knows how to appear as though he isn't really performing at all.

It could be that Reagan's plans and programs are just more political swamp gas, but the fact is, no president since Kennedy has shown a greater potential for cheering us up and fostering optimism, and all it takes is for him to be electronically disassembled in Washington and reassembled in the television sets of the nation.

Is there a danger in having a president with this kind of video dexterity? Oh, probably. An illusion can be made so attractive in the age of television that people cease caring whether there is any truth to it. Ronald Reagan could turn out to be the first President Feelgood, all grandfatherly solace and honey-graham voice, whose TV appearances are as resolutely uplifting as -- if no more realistic than -- an episode of "The Waltons."

Like Carter, Richard Nixon always looked uncomfortable on television, but in such an entertaining way! Wow! We won't see the likes of him again for awhile. Gerald Ford looked uncomfortable everywhere, and terribly propped-up on TV. And Lyndon B. Johnson abviously bristled inside at the cuddly, folksy image his advisers foisted on him for TV's sake.

Naturally, Reagan has his advisers, too, and they prefer to have him in controlled situations rather than unpredictable ones like press conferences. Reagan's first televised press conference was about as controlled as a press conference can be, at least in terms of forced decorum, but it did not show the president off to much advantage. If he says "I believe in linkage" one more time there may be a loud simultaneous national groan. Better the "shining city on a hill" than that.

In his economic talk, though, he was thoroughly in command -- natural, unmannered, neighborly and yet presidential as all get-out. The setting was unprecedented in one respect: Unlike almost every other TV presidential address, this one opened with a close-up, Reagan's face filling the screen, rather than the standard, and more respectfully distanced, medium shot that takes in the desk and surroundings.

This gave the talk intimacy and urgency from the very first moment. They said "here's the president" and here he was.

The conversational tone was inspired, especially on "Oh, don't get the wrong idea" when discussing taxes and business. "Now let me show you a chart I've had drawn," Reagan said a little later. It was a tacky chart; it did not look slick. "A low-budget production," said one Washington wag later, "and that's what people want. A low budget."

The Reagan talk had the flow, the directness, the persuasiveness of a very good commercial, even down to the cleverly deployed props of a dollar bill and some coins. In fact, if the president isn't careful, he'll start looking too much like Glenn Ford or Ike's brother or some other trusty duffer selling insurance.

Maybe the Reagan people are the slickest slickers ever -- so slick they don't look slick. The Carter people took the pose of feisty grass-rootsters who weren't going to play media games; then it evolved they were the most media-mad crowd yet.The awshucks hucksters turned out to be champion cynics.

Every president since FDR has had to suffer comparison to Roosevelt's Fireside Chats. Television is the new fireside; it's what people gather around for light, if not heat. Reagan may prove an even more adept chatter than Roosevelt was.Roosevelt was a radio president who declaimed and orated; Reagan is a television president who confides and reassures.FDR was bombastically galvanizing, Reagan quietly galvanizing.

The jabbery TV reporters who stumbled onto the air after the talk tried to introduce notes of friction about Reagan and Congress. It hardly seemed relevant, it even seemed churlish. Reagan had just done a sensational job of reaching the people. To make a perfect performance more than perfect, he ended with a dramatic pause between "Thank You" and "and good night."

What a president. Or, what an actor. Either way, a star is born. Again.