Between Intellectus, Visus and Auditus: Jean des Murs’s Musica Speculativa, Version A (1323)

The title of this paper draws attention to the description of the diagrams given by Jean des Murs in his Musica speculativa (Version A). He defines them as ‘sensible figures’ very much appreciated by mathematicians, because the truth which is in the intellect is, thanks to them, properly transmitted to the judgment of sight and hearing. This description refers the reader to three other questions that are crucial for understanding the treatise. These are: the place of music among the mathematical disciplines; the epistemological/cognitive process leading from intellect to sight, and then to hearing; and, finally, the structure of the treatise Musica speculativa as a reflection of the epistemological process leading from the numerical paradigm of the Pythagorean system to the actual sounds discernible by hearing. This study discusses the role of diagrams contained in the Musica speculativa, which are not so much memory aids (as is the case, for instance, with the manus Guidonis), but rather analytical tools and visual representations of mathematical theorems and operations, which constitute an integral part of the texts and give insight into the structure of the transmitted doctrine.