Epytoma Joannis de mo[n]teregio in Almagestu[m] Ptolemei
Johannes Regiomontanus(1436-1476)
 Although the details of Ptolemy’s life (different from Ptolemy I, the ruler of Egypt in the Ptolemaic dynasty) are not well established, he is known as an ancient astronomer and geographer born in Egypt. He studied at the “Museion” in Alexandria, similar to other scholars at that time. Ptolemy was a scholar in the field of astronomy and of geography, he comprehensively studied the geocentric theory (stating that the Earth is stationary at the center of the universe and that the sun, planets, and other stars orbit the Earth) that was supported by Anaximandros (6th century B.C.), Pythagoras (5th century B.C.), Plato (427–347 B.C.), Eudoxos (408–355 B.C.), Aristotle (384–322 B.C.), and Hipparchus (190–120 B.C.). Ptolemy added his own concepts to the geocentric theory in order to ensure that the astronomical observations matched the theory’s postulations, thereby establishing the geocentric theory. His theory that can be referred to as the Ptolemaic system successfully explained the “apparent” celestial movement. This theory was accepted for 1300 years until Copernicus challenged it in 1543 by proposing the heliocentric theory (or Copernican system), which stated that the Sun is stationary at the center of the universe and that the Earth and other objects orbit the Sun. Ptolemy’s book on the geocentric theory was later called “The Greatest Book on Mathematics” by Greeks and was transmitted to Arabia. The Arabs attached the definite Arabic article “Al,” calling this book “Almagest.”
 Johannes Müller, a German astronomer who named himself “Regionmontanus” (the Latin name of his native town Königsberg), was a passionate believer in the Ptolemy theory and epitomized “Almagest” and translated it into Latin. He published this book by adding his own annotations. The book is the second publication on Ptolemy’s theory and it has been said to be the most beautiful version.