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The perfect fifth we know already from the common chord.
To the superfluous fifth belong the major third and perfect octave.
The diminished sixth is accompanied by the minor third and diminished seventh.
To the major and minor sixth we usually add the major or minor third and the octave; and we already know this chord as the first inversion of the perfect common chord.
To the superfluous sixth belongs either the doubled major third, or the major third with the superfluous fourth. Instead of this latter interval, the perfect fifth may also be taken.
