The main influence on al-Farabi's philosophy was the Aristotelian tradition of Alexandria. A prolific writer, he is credited with over one hundred works. Amongst these are a number of prolegomena to philosophy, commentaries on important Aristotelian works (such as the Nicomachean Ethics) as well as his own works. His ideas are marked by their coherency, despite drawing together of many different philosophical disciplines and traditions. Some other significant influences on his work were the planetary model of Ptolemy and elements of Neo-Platonism, particularly metaphysics and practical (or political) philosophy (which bears more resemblance to Plato's Republic than Aristotle's Politics). }