Is music just matter of hearing and producing notes? And is it of interest just to musicians? By exploring different authors and philosophical trends of the Roman Empire, from Philo of Alexandria to Alexander of Aphrodisias, from the rebirth of Platonism with Plutarch to the last Neoplatonists, this book sheds light on different ways in which music and musical notions were made a crucial part of philosophical discourse. Far from being mere metaphors, notions such as harmony, concord and attunement became key philosophical tools in order to better grasp and conceptualise fundamental notions in philosophical debates from cosmology to ethics and from epistemology to theology. The volume is written by a distinguished international team of contributors.