How Jews Helped Discover the Real World

Jewish Contributions to Humanity #1:
Original research by Walter L. Field.
Sponsored by Irwin S. Field.

ABRAHAM CRESQUES (1325-1387) b. Majorca, Spain.
The Mapmaker. A distinguished Spanish mapmaker and compass expert from the island of Majorca, Cresques was a leading member of the Majorcan cartographic school, a term attributed to the mostly Jewish cartographers and navigational engineers who had a huge impact on exploration until the Spanish Inquisition in the 15th Century. Prince John of Aragon tasked Cresques and his son, Judah Cresques, with designing that day’s most accurate maps to describe and illustrate the world as it existed west of the Strait of Gibralter. Their work became known as the Catalan Atlas, the most important Catalan map of the Middle Ages.

ABRAHAM ZACUTO (1452-1515) b. Salamanca, Spain.

A guide for Columbus. The impact of Jews on navigation was so profound that had it not been for Zacuto, the discoveries of Christopher Columbus and Vasco de Gama (the first European to reach India by sea) may not have happened. Zacuto, a Spanish rabbi, astronomer, mathematician, and historian, created the first truly useful astrolabe for marine navigation. His astrolabe helped determine a ship’s latitudinal position by using the position of the sun. And his astronomical tables were used by Columbus and de Gama, who was thoroughly consulted by Zacuto before his 1496 voyage to India.

Legend has it that Zacuto’s astronomical tables may have actually saved the lives of Columbus and his crew when natives in America attacked them. Columbus told the natives that if he was harmed, he would extinguish the sun and the moon, depriving them of light. Why did the natives believe him? Because Columbus—using Zacuto’s astronomical table—accurately predicted an eclipse that appeared.

Another Jew who played an integral role in Columbus’s discovery of the New World was Luis de Torres, the interpreter on Columbus’s first voyage and the first Jew to settle in America. He converted to Catholicism just before the voyage in order to avoid an expulsion edict against Spain’s Jews. Sent by Columbus to Cuba, de Torres was warmly greeted in an Indian village and it was there that he became the first European to ever encounter tobacco.

LEVI BEN GERSHOM (1288-1344) b. Bagnols-sur-Cèze, France.

The rabbi astronomer. One of the most brilliant and least known Jewish philosophers, Rabbi Levi was a pioneering 14th century French mathematician whose invention, the Jacob’s staff, could determine the angles between landmarks and celestial objects, such as the horizon and the moon, an exceedingly useful tool for explorers for about 200 years. Rabbi Levi, also known as Gersonides, may have also been the first astronomer to accurately determine stellar distances—the distance between stars, by discovering that the stars did not rotate around the earth. His refutation of the Ptolemaic or geocentric model helped lead to Copernicus’ heliocentric model.