The main desire of Ptolemy in writing his Almagest is to explain and account for the motions of the apparently erratic celestial beings in terms of perfect and circular motions. In doing so he introduces the epicyclic (which states that the center of a smaller circle orbits around the earth and the object orbits around the smaller circle) and the eccentric hypotheses (which supposes that the center of the circular motion of the planet is not exactly centered on the earth), which are ultimatly equivalent to eachother in terms of result. Begining with the motion of the sun in the sky and moving on to the less accountable outer planets, Ptolemy moves his mathematics brilliantly with a nod to a story teller's art. Some may find his introduction of his equant (something that is often said to defile his principles of perfect motion), which explains the retrogradation of the outer planets, to be a let down to the fanfare of perfection in the stars. Yet, overall, the Almagest manages to recapture the magic and wonder of the universe through complicated mathematical hypotheses and to succesfully lay the ground for the break throughs of Copernicus, Brahe, and Kepler to come. If you are at all interested in astronomy or mathematics, you ought to read this.... More • http://amzn.to/1MZdQr5 View • Books • Images • Videos • Search Related • Science • Books