Traité de l'harmonie réduite à ses principes naturels

A fundamental work in the development of Western music, it earned Rameau a reputation as the most learned musician of his time.

The Treatise summarizes the efforts of its author to make music a science, when before him it was considered an art.

Rameau takes up the work of his predecessors, notably Zarlino and Descartes (Compendium musicae), to bring order to the scattered notions identified before him and make harmony a deductive science like mathematics, on the postulate that “sound is to sound as string is to string” (referring to the mathematical relation between pitch and length).

It states the principle of the equivalence of octaves, the notions of the fundamental bass and the inversion of chords, the pre-eminence of the major triad and, at the cost of an intellectual contortion (one of the weaknesses of the theory), that of the minor perfect chord.

A few years later, he saw that striking confirmation of his theory, which gave rise to the publication of a complementary treatise, Harmonic Generation.