How did Jean Le Rond d’Alembert explain Jean-Philippe Rameau’s musical system?

Jean Le Rond d’Alembert explained the musical system of Jean-Philippe Rameau in his 1752 work, Éléments de musique.1

In this text, d’Alembert attempted to expound the principles of Rameau’s harmonic system, which had consolidated contemporary musical developments into a framework that dominated Western music until the early 20th century. Rameau’s theory, which d’Alembert sought to clarify, is centered on the concept that all harmony is derived from the "root" or fundamental note of a chord, with other notes arranged in thirds and fifths above it.12

While d’Alembert was a proponent of Rameau’s technical musical theories, he was also a member of the Encyclopédie group that championed Italian music during the "controversy with Rameau," a debate that pitted the priority of melody against Rameau’s insistence on the priority of harmony.3