What is the theory of Ptolemy?

Ptolemy also wrote an influential work, Harmonics, on music theory and the mathematics of music. After criticizing the approaches of his predecessors, Ptolemy argued for basing musical intervals on mathematical ratios (in contrast to the followers of Aristoxenus and in agreement with the followers of Pythagoras), backed up by empirical observation (in contrast to the overly theoretical approach of the Pythagoreans). read more

Ptolemy credited Hipparchus (mid-2nd century bce) with essential elements of his solar theory, as well as parts of his lunar theory, while denying that Hipparchus constructed planetary models. Ptolemy made only a few vague and disparaging remarks regarding theoretical work over the intervening three centuries, yet the study of the planets undoubtedly made great strides during that interval. read more

(See Ptolemy's theory of the solar system.) In the first book of the Almagest, Ptolemy describes his geocentric system and gives various arguments to prove that, in its position at the center of the universe, the Earth must be immovable. read more