This chapter traces philosophy of music from its origins until the end of the classical period. Four major questions dominated ancient philosophy of music. Ancient philosophers asked about the nature of music, and they debated whether music is a mimetic (imitative) art. The second question concerned the relationship between musical harmony and the world. Many ancient philosophers believed that musical harmony provides the key to understanding reality, including the human soul and the motions of celestial bodies. The third question concerned the value of music. Some philosophers held that music is valuable as a source of pleasure, while others believed that music could improve or corrupt the characters of listeners, and still others talked about the beauty of music. The final question concerned musical genius and the Platonic and Longinian accounts of genius emerged. Pythagoras, Plato, Aristotle, Aristides Quintilianus, Lucretius, the Epicureans, Augustine, Quintilian, Boethius, Sextus Empiricus, Ptolemy and Longinus are among the writers discussed.