In Echoes of an Invisible World Jacomien Prins offers an account of the transformation of the notion of Pythagorean world harmony during the Renaissance and the role of the Italian philosophers Marsilio Ficino (1433-1499) and Francesco Patrizi (1529-1597) in redefining the relationship between cosmic order and music theory. By concentrating on Ficino’s and Patrizi’s work, the book chronicles the emergence of a new musical reality between the fifteenth and sixteenth centuries, a reality in which beauty and the complementary idea of celestial harmony were gradually replaced by concepts of expressivity and emotion, that is to say, by a form of idealism that was ontologically more subjective than the original Pythagorean and Platonic metaphysics.