Johannes Kepler (1571-1630) was a German mathematician, astronomer, and astrologer. A key figure in the 17th century scientific revolution, he is best known for his laws of planetary motion, based on his works Astronomia nova, Harmonices Mundi, and Epitome of Copernican Astronomy. These works also provided one of the foundations for Isaac Newton’s theory of universal gravitation.
Chandler B. Beach The New Student's Reference Work for Teachers Students and Families (Chicago, IL: F. E. Compton and Company, 1909)