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.

We call ourselves Americans today because of the map’s makers, Martin Waldseemüller and Mathias Ringmann, young clerics in the cathedral village of St.-Dié, France. By incorporating early New World discoveries, their map reached beyond the canonical descriptions of Old World geography handed down from Ptolemy in the second century. On a lower stretch of the southern continent, the mapmakers inscribed the name “America” in the mistaken belief that Amerigo Vespucci, not Columbus, deserved credit for first sighting a part of that continent, South America.

Or possibly they favored Vespucci because he held more firmly to the growing consensus that this was indeed a New World, not the Indies (as Columbus so wanted to believe), and because he wrote more colorfully than Columbus about the people he encountered.