HE WAS A GANGLING rural teen-ager, a bit homesick at his city school and in love with his books. He fell apart when someone suggested his favorite novel, a sort of compendium of Wild West stories called The Romance of the Three Kingdoms , was not the literal truth. He drew up a petition demanding the mayor to fire the school principal who had debunked the book. He threw chairs at a schoolmate who supported the principal. "You're a traitor. I'll kill you," he said.

The heartsick youngster was Mao Tse-tung, so wedded to his fantasises, so sure of himself, and so unbelievably lucky, that he turned his life into a story no reasonable novelist would invent. He eventually became the Washington, Jefferson and Lincoln of the most populous empire ever on earth, and these two biographies are the first to appear since his September 9, 1976 death. In very different ways, Wilson and Terrill saw how engrossing the story of Mao's life remains, and why it has become so difficult for his heirs to chisel away his legend.

In Peking, where I live, they have taken down at least temporarily the huge portrait of Mao that has dominated Tiananmen Square for more than two decades. The building holding Mao's refrigerated, embalmed body is often closed for months and his writings receive far less attention now in the official press. But so far no one dares attack him directly. Mao is China, at least in this century. Both the carefully documented, straightforward story told by Dick Wilson and Ross Terrill's more personal, feverish account show how much the lives of nearly a billion Chinese are wrapped up in the 82 years Mao spent on earth They also provide some basis for the rest of us to understand what is to come. tAs Terrill says, "Mao became known to the world outside China to a degree that no figure in China's 3,000 years had ever been before." Tales of this strange political guru of the East led many Americans of my generation to discover China in the 1960s, and not be able to turn away. In a tragic, unsuccessful effort to destroy the political heirs whose pragmatism he distrusted, Mao in his last years became an ideological cyclone, devastating to his surroundings but fascinating to watch from a distance. Earlier biographers, such as the thoughtful Stuart Schram, had told his story well up to the cultural revolution of the late 1960s. Wilson and Terrill bring it to a dramatic close.

Like most Mao watchers, the two men feel compelled to separate Mao early on from the Marxist doctrine that seemed to distort the world's view of him. "He chose Marxism as his weapon, because that happened to come into fashion at the time when he needed a weapon," said Wilson, a British Sinologist who edits the prestigious China Quarterly and writes a lively newspaper column on Asia. His book flows smooth as the Yangtze, using the best and most absorbing materials from the rather sketchy available records of Mao's life. Wilson graciously lets the story tell itself, providing an insight here and there. Of young Mao's annoyance at being at first ignored by the great men of Peking because of his abrupt manner and thick southern accent, Wilson says "It is striking that the other great lonely dictators of modern times -- Napoleon, Stalin and Hitler -- all suffered from the same disadvantage."

Terrill is a brilliant, prolific Australian, a former Harvard government professor whose colodful book 800,000,000: The Real China illuminated the People's Republic for many Americans just as Nixon touched down in Peking in 1972. Terrill uses his vivid style to fill gaps in the available materials on Mao's life. He also adds fascinating bits of information from what appear to be his own personal sources in China, though unfortunately he cannot for now tell us much about them.

Terrill jumps, darts, hammers at his subject. He guesses, probes, tries to tie ends together. From Mao's quote that he "did not sympathize" with his father after hungry peasants stole some of his grain, Terrill concludes: "The connection of ultimate force for Zedong [Terrill uses the pinyin spelling of Mao's given name] had been made: his nasty father was a local linchpin of the unjust social order of old China . . . The old man was a lion in the path of China's true salvation; the adolescent now drew this chilly conclusion. Zedong's terrible words about his father took on their full meaning: 'I learned to hate him.' He linked his life as a boy with the life of his stimes." The technique is sometimes annoying, sometimes fascinating, but it does shed interesting light on some dark corners.

Wilson, for instance, handles with characteristic modesty the important and mysterious 1971 death of Mao's heir apparent, defense minister Lin Piao. He sums up in a paragraph the incredible, official story of an attempt to assassinate Mao by Lin henchmen, followed by Lin's frantic flight towards the Soviet Union which ends in a fiery crash. "Only the Maoist side is known," Wilson says, "but the least that can be said is that [Lin] was incapable of organizing a successful assassination."

Terrill devotes several pages to the tale, picking at it like a rain-soaked knot. From the fact of a top-level party meeting before Lin's alleged escape and from the inconclusive information about the bodies on the plane, he suggests the crash was a decoy. Lin's death "could have been suicide, or a death from illness while in detention sometime before mid-September"; but Terrill concludes "it was probably murder," perhaps murder by Mao.

Mao's political heirs, sitting atop piles of Mao papers and records of private conversations, have not seen fit to help unravel these mysteries yet. More may be learned if the long-delayed trial of Mao's widow and her Shanghai allies, the infamous Gang of Four, ever comes off. Wilson, Terrill and biographers to come may have to revise a bit and take another look at their sources, but they have the essence of the life here.