Ptolemy. Historical artwork of the 2nd century Greek-Egyptian astronomer Ptolemy (Claudius Ptolemaeus). Ptolemy wrote four major books, the most influential being Almagest. In this work, he collated over 500 years of Greek astronomical thinking. Almagest lays out the universe with the Earth at its centre and all bodies revolving around it. This view persisted until Copernicus's theories some 1300 years later. Ptolemy's other books were concerned with geography and cartography, optics and astrology. These too remained important texts until the scientific revolution of the 16th and 17th centuries.