BILL Moyers, the television commentator, has been ''walking through the 20th century'' recently and stopped at my house. My wife thought at first this would be fine, and she would make lemonade. Little did she reck. The first wave arrived around 8 a.m. They came in an oversize moving van. Cables ran outdoors to the van, which was called a portable control room. In no time the downstairs was looped for sound and I saw articles of furniture taking flight around the house. Somebody seemed to be coming out from under every sofa. The caterer brought lunch for everybody around noon. The commotion almost blocked Garfield Street.
The soft-voiced Bill Moyers was searching for something and I thought I guessed what it was. He is the only man I know who is accompanied by a traveling historian, the erudite Bernard Weisberger, whose job it is to help find appropriate film clips to fill hiatuses on the screen in what they quaintly call ''footage.''
Moyers himself could only have happened in the 20th century. He was born 50 years ago in a remote corner of Oklahoma, and once had a job with an ambitious senator from Texas, Lyndon Johnson. He picked up a year's theological course at the University of Edinburgh in 1957. At one time he was at the University of Texas at Austin, where he could combine courses in journalism with experience as an assistant news director of KTBC (a TV station Mrs. Johnson owned). Besides attending classes and working a 48-hour week at the station, he preached at two small Baptist churches on alternate Sundays.
What Moyers is now trying to explicate, I think, is what America is and what it seeks to be. His parallel on the screen between the rise of Franklin D. Roosevelt and that of the infamous Adolf Hitler is one of the most brutal and deeply stirring things I have ever witnessed. Roosevelt? Why yes, I remember him. I went to nearly all his press conferences. In 1932 I was out with him and Sen. George Norris on the prairie fairgrounds at McCook, Neb., when Roosevelt was running for president. As he spoke he was bathed in the most brilliant sunset that ever happened.
Changes in history? This was one of them! America had a mystical belief in those days in two things, isolationism abroad (shattered by Pearl Harbor) and government nonintervention at home in what was loosely called ''free enterprise.''
''Free enterprise?'' Here's what the unfortunate Herbert Hoover said in a TVA veto message which I heard the clerk read to Congress. Calvin Coolidge vetoed the first Muscle Shoals bill; now it was Hoover's turn. (President Wilson in World War I lamented the wastage of power in Muscle Shoals, where the stream dropped 137 feet in 37 miles.) Norris noted that in Canada the government ran the hydro program; why not here? Hoover explained:
''I hate to contemplate the future of our institutions, of our country,'' he said, ''if the preoccupation of its officials is to be no longer the promotion of justice and equal opportunity, but is to be devoted to barter and the market. This is not liberalism, it is degeneration.'' Hoover made the decision plain, in black and white.
So this was one of the great divides; the difficulty for voters and journalists and historians is generally to know when they occur. Personally, I liked Hoover. He was unfortunate. His record in Belgium was inspiring. But I had a sense that evening, as the sunset throbbed and pulsated in McCook, and as FDR and Norris exchanged pledges, that this was a moment to remember. When FDR was inaugurated, he sent a note to Norris, the cherub-faced maverick with the black bow tie (whom FDR called ''the very perfect gentle knight of American progressive ideals'') saying that he had not forgotten. He signed a new TVA bill May 18, 1933.
Was he right? Historians Samuel Eliot Morison and Henry Steele Commager in the ''The Growth of the American Republic'' say, ''. . . the change involved . . . a candid acceptance of socialism in the realm of public utilities and a commitment to the experiment of a planned economy.''
It provided for the rehabilitation of an area three-fourths the size of England. We have accepted it. Today historical snoopers search out past footsteps. I think of it as the quiet-voiced Bill Moyers asks questions about old times.