Boethius and Ptolemy on harmony, harmonics and human music

The contribution analyzes how Boethius elaborates the concepts of vis  or facultas armonicae  (power of the harmonics) and vis armonica  (harmonic power), both derived from Ptolemy’s dynamis harmonike, namely the powerto grasp the distinctions between high and low sounds and produce an immediate judgment of pleasure or distrust. The essay aims to demonstrate that this concept provides the theoretical equipment for the study of the Boethian second genus  of music, the musica humana , and consequently that Boethius’ famous threefold division of music (instrumentalis , humana  and mundana ) implies a special methodological approach for each area. In particular, with the unfinished book 5  of the De institutione musica , Boethius turns to the practical usefulness of music, and shifts from a pure mathematical science, the instrumentalis , to an intermediate one, the humana , which involves also ethics and physics. For Boethius, this second kind of music concerns human wellness and good government, and its knowledge is particularly recommended to rulers and those who have political responsibilities.