A DECADE AGO, the Library of Congress paid $10 million to acquire the only known original copy of a 1507 world map that has been called “the birth certificate of America.” The large map, a masterpiece of woodblock printing, has been a star attraction at the library ever since and the object of revived scholarly fascination about the earliest cartography of the New World. The research has also rescued from obscurity a little-known Renaissance man, the 16th-century globe maker Johannes Schöner, who was responsible for saving the map for posterity.