I'm not sure that I can agree with your reasoning, greg.

I am no expert on early music, but I am quite certain that from the earliest days composers, in addition to the dominant seventh chord, would frequently have incorporated a flattened seventh in the tonic major chord in order to provide a resolution to the subdominant chord.

Incidentally, does anyone know at what point in musical history the "naming" of chords began? Did Beethoven and Bach ever refer to C7 and G9th ?

Murray