New System of Musical Theory
New System of Musical Theory (French: Nouveau système de musique théorique) published in 1726, is the second treatise on musical theory written by the composer Jean-Philippe Rameau. Rameau wrote the work four years after the publication of his first theoretical work, the Treatise on Harmony Reduced to its Natural Principles (French: Traité de l'harmonie réduite à ses principes naturels) (1722).
Source: Wikipedia — New System of Musical Theory (CC BY-SA 4.0)