History doesn't repeat itself so much as it recycles the elements of human existence.

War, plague, religion, conquest - they keep coming up with a different cast of characters.Variations on the themes of history come alive in Timeline (9 p.m., Ch. 11), a six-part re-enactment of major historical events of the Middle Ages.

Each of the six medieval milestones is treated as though it were being covered by modern TV news techniques. Steve Bell, former news anchor of ABC's "World News This Morning" and "Good Morning America," mans the anchor chair.

Viewers with long memories will realize it isn't only history that recycles itself - so does television.

From 1953 to 1957, CBS broadcast a re-enactment of history as news events titled "You Are There," anchored by Walter Cronkite. He signed off saying, "What sort of day was it? A day like all days, filled with those events that alter and illuminate our times - and you were there."

Even that wasn't original - "You Are There" was first heard on CBS Radio in 1947, with host John Daly.

The first "Timeline" focuses on "The Crusades." Later it's "The Black Death," "The Vikings," "The Fall of Byzantium," "The Mongol Empire" and "Granada."

"One of the fascinating things about this for me," Bell said in an interview, "was to realize what might have happened if there had been television then.

"Take the Crusades. Here are the men off in another part of the world, fighting and dying - for what? What if daily reports had gone back to Christendom about how, when the Crusaders got to Jerusalem, they slaughtered the local population? Would people have allowed the occupation of Jerusalem? Would we have a different history?"

The television experience in Vietnam comes to mind.

"Or take the Black Plague," Bell continued. "As that program begins, the plague is decimating Europe but there are no reported cases yet in the British Isles. It hasn't come across the English Channel - yet.

"We have our own plague - AIDS . . ."