The ambiguous title of this paper is intended to suggest two themes which I would like to develop: (I) music as it was conceived by, and of particular interest to, philosophers in Late Antiquity, in particular the Neoplatonic philosophers of the fourth, fifth and sixth centuries (Iamblichus, Syrianus, Proclus, Damascius, Olympiodorus); and (II) the impact of music, as these philosophers conceived of it, on the way in which they approached other areas of inquiry.