Claudius Ptolemy was a Greek mathematician, astronomer, geographer, astrologer and poet believed to have been born in 90 AD in a town named Ptolemais Hermiou in Thebaid. However according to some historians he lived his whole life in Alexandria. Only a few details about his life are known. Some believe he was a Roman citizen but other scholars say he was Greek and is known to have used Babylonian data for his astronomical findings.
Ptolemy said that he used selected astronomical observations that were made by his predecessors eight centuries ago, to derive his geometrical models. He used tables to present his models. These tables could also be used to calculate the position of the planets. Ptolemy’s geocentric models were accepted till the heliocentric models were introduced during the scientific revolution. ‘The Almagest’ was the only treatise that had survived presenting astronomical techniques and star catalogues. At first its name translated in English meant ‘The Mathematical Compilation’ which was later changed to mean ‘The Greatest Compilation’. He also introduced a useful tool for astronomical calculations in his ‘Handy Tables’. These tables had all the data needed to calculate the position of the sun, moon and other planets. It could also compute the rising and setting of the stars and solar and lunar eclipses. Ptolemy’s mathematical works consists of theorems and geometrical proofs. He describes his work in the following words:
‘We shall try to note down everything which we think we have discovered up to the present time; we shall do this as concisely as possible and in a manner which can be followed by those who have already made some progress in the field. For the sake of completeness in our treatment we shall set out everything useful for the theory of the heavens in the proper order, but to avoid undue length we shall merely recount what has been adequately established by the ancients. However, those topics which have not been dealt with by our predecessors at all, or not as usefully as they might have been, will be discussed at length to the best of our ability’.
Other major works by Ptolemy include ‘Geographia’ which is a compilation of world geography known to people in the Roman Empire during his time. He was also very well known as an astrologist. He is mentioned to as a ‘pro-astrological authority of the highest magnitude’. His astrological treatise ‘Tetrabiblos’ was a series of four books and is said to have had almost the same importance as the Bible to people of that time. His work ‘Optics’ was about light and its reflection, refraction and color. Ptolemy’s expertise did not restrict only to the mathematical fields but he also wrote a highly significant work on the music theory called ‘Harmonics’.
Ptolemy died in 168 AD at the age of 78. His epigram, which he is said to have written himself read:
Well do I know that I am mortal, a creature of one day.
But if my mind follows the winding paths of the stars
Then my feet no longer rest on earth, but standing by
Zeus himself I take my fill of ambrosia, the divine dish.