Johannes Kepler is best known for his discovery of the three laws of planetary motion, demonstrating that the universe operates according to fixed, natural laws. A disciple of the great astronomer Copernicus, Kepler refined and advanced Copernican theory. After the death of Tycho Brahe, a leading astronomer of the 16th century, Kepler was appointed Imperial Mathematician in Prague by Emperor Rudolph II. His many published works describe his search for the mathematical accordances on which the universe is structured, and his study laid the foundation for the understanding of the cosmos, out of which grew the science of modern astronomy. Isaac Newton's work in universal gravitation was influenced by Kepler's discoveries and the standards he set for scientific inquiry. Kepler's research in light refraction resulted in two important books on the subject of opticsand improvements in the astronomic telescope. As a mathematician, his efforts to complete Brahe's...