Giant Ginkgo

''Zheng set sail in 1421,'' Menzies said. ''The famed Treasure Fleet junks were five times larger than Columbus's caravels. Each held a thousand men. Two years later, in 1423, seven ships returned. Then, in a decision that would change all of history, the Ming emperor ordered all the ships dismantled. He pensioned off the sailors. And he burned all the records.''

Traditional historians would agree with Menzies that in 1423 China abruptly abandoned exploration and turned inward after the Treasure Fleet returned from sailing no farther west than Kenya. But Menzies, a self-taught historian publishing his first book at age 65, says that he has found evidence proving that the Chinese didn't turn around after Kenya -- but rather rounded the Horn of Africa and discovered the New World.

At a time when big books must declare an end of something or a theory of everything, Menzies has accomplished both. His thesis upends the entire Western age of discovery, from Columbus to Cook, and shifts the achievements and adventure from Europe to Asia. Figures like da Gama and Pizarro are written off as war criminals and replaced with a peaceful Chinese trading mission that supposedly charted all seven continents (even the North Pole). As to America, Menzies says that he has found proof that the Chinese thoroughly explored the East Coast from what is now Florida to Rhode Island. On the West Coast, he argues, they sailed into San Francisco Bay -- humiliatingly running aground upriver near Sacramento. Another Chinese fleet checked out the center of the continent, especially Missouri, and at some point lost another ship in Kansas.