Ptolemy

Real name: Claudius Ptolemaeus

Little is known about the life of the most famous astronomer and astrologer of antiquity. He is thought to have lived between 100 and 160 BCE, according to some sources 10 to 15 years earlier. He was of Greek origin and was influential in Egyptian Alexandria.

Ptolemaeus (known in English as Ptolemy) saw no distinction between science and astrology. His work Almagest (or: "Megale syntaxis tes astronomias") was a collection of the writings of earlier Greek astronomers. Among other things it deals with the calculation of solar and lunar eclipses and contains theories on the Sun, Moon, planets and the fixed stars together with an astronomical catalogue of 1028 objects. This knowledge helped astronomers of modernity to calculate the movement of the fixed stars. Ptolemy also developed the geocentric model of our solar system (a fact reflected in the alternative term Ptolemaic model) which, along with most of his other theories, influenced human thought in this field up until the Copernican revolution. The widespread speculations among his contemporaries (the most famous being the astronomer Aristarchos) about the possibility that the solar system might be heliocentric were soon forgotten after the publication of the Almagest which helped to establish the geocentric model for over a thousand years.

Ptolemy's work "Tetrabiblos" (four volumes) became one of the most important works in the history of astrology. In it he systematised the astrological knowledge of his time and made important contributions to the fields of individual astrology and [[mundane astrology]], the houses, zodiac, elements, planetary interpretation, prediction and the aspects. Ptolemy made the decisive step of combining the zodiac with the planetary positions (History of Astrology). The fixed stars outside of the zodiac lost their astrological significance. In the introduction he wrote: "Essentially, the interpretaion of the heavens is based on two scientific branches. The one, astronomy, teaches us about the movement of the Sun, Moon and stars, their position at any given moment, both in regard to each other and to the Earth. The other, astrology, observes the changes and influences caused by the heavenly bodies, depending on their inner powers and the influence of their respective positions. The former (astronomy) requires an independent mental penetration and is valuable, even though it is not interested in interpretation. But I would now like to mention the latter (astrology). Its validity may not be so established and complete, but I believe it is possible to understand it by way of philosophical reflection ..."