Broadcasting made politics both more "real" and more illusory. Radio and television took the candidates off the streets and put them in our homes, but it put them there as electronic shadows -- first, on radio, as disembodied voices, later, on TV, as ghosts behind glass.

Of course, radio and TV don't just bring us politicians as they are; they bring us politicians as they want to be, or as they want to be perceived. In this election year, even though as much attention is being paid to the media as to the candidates, there is still much to be said about the relationship between television and democracy.

Tonight at 9 on Channels 26 and 32, Bill Moyers will say some of it on an exceptionally thoughtful and thought-provoking edition of "A Walk Through the 20th Century." In "The 30-Second President" Moyers traces the history of TV political commercials through presidential elections starting in 1952, and he talks with two fascinating experts in the field: Rosser Reeves, the dean of "hard-sell" advertising, who was interviewed by Moyers shortly before his death in January, and Tony Schwartz, the perception engineer and media guru who created some of the most pungent political spots ever.

Standing next to a TV set, Moyers says, "No single force has changed American politics more than this little box." Reeves was a significant part of that change, because in the '50s he modified the techniques he had used to push candies and antacids for use in political campaigns. That is, Reeves sold America Eisenhower about the same way he sold America Anacin. In this, Reeves was a pioneer. "It was inevitable that it had to happen," he told Moyers of the merger between Madison Avenue and politics. "I was merely the first one to do it."

Moyers replays the wham-wham Anacin ad that made Reeves famous, and anyone who grew up with TV in the '50s will probably recognize it at once, and painfully -- not just recognize it but recite along with it from memory: "Three out of four doctors recommend the ingredients in Anacin . . . Fast, fast, fast relief."

Reeves told Moyers that Anacin's sales "went through the roof" because of the commercial, which showed cartoon jackhammers going off in a cartoon head. He also said, with no hint of guilt, "It was perhaps the most hated commercial on the air at the time."

For Dwight D. Eisenhower's campaign, Reeves didn't hit the viewer quite so hard, but the ads when shown again now are tough, direct, and almost childishly simple. ("You have to be simplistic" in advertising, Reeves said.) Many of them were keyed to the theme "Eisenhower Answers America" and featured Ike responding to questions posed by "average citizens." Of course, the questions were filmed separately and Eisenhower filmed his answers talking stiffly to nobody but the camera.

Reeves recalled of Eisenhower, "The general was a singularly inept speaker," but he also turned out to be a trouper, filming nearly 40 of the commercials in one day, then turning to Reeves as he left and sighing, "To think that an old soldier should come to this."

The strangest thing: in these early spots, both in person and in caricature, Eisenhower looks like a benign Don Rickles. Or maybe Don Rickles' grandfather.

It seems a long way from the crude basics of the Eisenhower ads to the more sophisticated manipulative approaches of the '60s and '70s. That's where we meet the brilliant Tony Schwartz, who works his magic out of a cluttered house on the East Side of New York City. Schwartz is the man who invented the famous anti-Goldwater commercial (in which Goldwater was never mentioned): the little girl with the daisy who is interrupted by the atom bomb and the voice of LBJ saying, "We must either love each other -- or die."

Time has not diminished the power or bizarre beauty of this classic, which was shown only once during the 1964 campaign and then withdrawn, but apparently will be discussed forever. Schwartz tells Moyers he thought the ad was perfectly fair. Moyers, who was liaison to Madison Avenue for LBJ at the time, doesn't seem to have made up his mind about that yet.

Schwartz also notes, "The campaign takes place in the living room now, not on the street." He tells Moyers, "We're not interested in public speaking. We're interested in private speaking." And he says, as he has in previous interviews, that America's three political parties now could be said to be ABC, CBS and NBC. Schwartz believes that political commercials do not trivialize issues of the day but in fact bring them into the foreground more readily than politicians do. But Moyers notes, with obvious regret, that to his knowledge none of the spots of the '64 campaign dealt with what would become the most traumatic issue of the 1970s, the escalating war in Vietnam.

Among the other commercials shown by Moyers: Schwartz's still- amusing laughing anti-Agnew add ("This would be funny . . . if it weren't so serious"); Ronald Reagan speaking on behalf of Goldwater and against those nasty "distorters of the truth," presumably the media; and one of the overly obvious Gerald Ford ads of 1976 that burbled, "I'm feeling good about America, I'm feeling good about me." This year's Pepsi-like Reagan ads are a quantum leap up from that and also a bit more frightening.

From New York, Schwartz recently said he thinks this Moyers program is the best TV show yet done on this subject. "All the other shows were trying to cover the subject and this one uncovers it," he said. Schwartz was also interviewed for the syndicated "Television and the Presidency" special earlier this summer but said he thinks that program was limited to "little snippets of things" and that the producers "didn't flesh anything out." That program had breadth; the Moyers program has depth.

The relationship between broadcasting and politics has been discussed and debated since the '20s, when this became a radio republic. Moyers won't have the last word, but on "Walk Through the 20th Century" there are plenty of provocative new words. The more people understand the medium, the better they will be able to translate the message.