Jean-Philippe Rameau · section 12 of 109

Chapter nine

Observations on All the Preceding Chords

We should now be convinced that the differences among perfect chords and seventh chords consist only in the different placement of thirds, or a reversal of their order. Accordingly, these chords have never been distinguished by other names, because modulation obliges us to use particular sounds, which determine the order of the thirds composing every chord. Once modulation is determined by the difference in the third occupying the lower position in either perfect chord, we can no longer avoid conforming chords to the order of the sounds contained within the octave of that perfect chord's fundamental sound. Yet despite the perfect chord's power in modulation, the seventh chord of Article III is independent of it. It is first in its kind and never changes, whatever form the perfect chord takes; it alone belongs to dominants, and without its aid a conclusion cannot be felt perfectly. It is the source of every dissonance. The major third it takes from the perfect chord from which it derives forms all major dissonances; the minor third added to that perfect chord to compose this one forms all minor dissonances. Moreover, after generating several chords by inversion or by adding a new lower sound beneath its foundation through supposition, it generates an equal number again by yielding its foundation to another sound, without any alteration in the place it must occupy. The other seventh chords, by contrast, owe everything perfect in them to this first one. They possess only the minor dissonance, and modulation determines their place. Hence every derivative of this first dissonant chord is distinguished by a name belonging to it alone, whereas the derivatives of other seventh chords share a common name, because they determine nothing and are themselves determined by modulation.

From all the observations contained in this chapter, we must conclude that harmony contains only two chords, the perfect chord and the seventh chord, and likewise only two dissonances, major and minor, as everything that follows will clearly prove.

The nature and properties of each interval and chord are reserved for Book II.