Philo’s interest in music is as known as it is overlooked in its philosophical implications. This chapter focuses on the importance of the musical paradigm in Philo’s thought and its relation to the other complementary model adopted by the philosopher: the pattern of the scala naturae, inherited from Stoicism. More specifically, Philo’s appeal to the notion of harmony introduces the idea of some orderly discontinuity in nature, implying both the transcendence of God and the limited condition of human rationality: the world is indeed governed by harmony, but only in the very qualified sense that it implies harmonically defined relationships between very distant entities. This ‘vertical’ harmony, however, is combined with a ‘horizontal’ one, for God also exerts his providence through harmony, while, in turn, music is the intellectual means by which man can contemplate the heavens and draw closer to God. These are not mere metaphors, for music represents a proper philosophical model for Philo that he applies to aspects which will prove fundamental in the post-Hellenistic age.