Claudius Ptolemy (100 –170) was a Greco-Egyptian writer, known as a mathematician, astronomer, geographer, astrologer, and poet. He lived in the city of Alexandria in the Roman province of Egypt, wrote in Koine Greek, and held Roman citizenship. Beyond that, few reliable details of his life are known.
Ptolemy was the author of several scientific treatises, three of which were of continuing importance to later Byzantine, Islamic and European science. The first is the astronomical treatise now known as the “Almagest;” the second is the “Geography” used by Christopher Columbus; and the third is the astrological treatise in which he attempted to adapt horoscopic astrology to the Aristotelian natural philosophy of his day, “Tetrabiblos.”