63
a resolution; that is to say, that the dissonant interval must be resolved into a consonant one; and this resolution must therefore naturally at last take place on a concord.
Among all the chords practicable in music, there is only one in each key which is called the perfect common chord, or perfect triad. It consists of a bass note or root, its third, its fifth, and when in four parts, the perfect octave also: viz.
The third may be either major or minor, according as the key is major or minor; but the fifth and octave must be perfect.
I must once more remind you that all the intervals in each chord are always computed and sought for from the lowest note upwards.
In the two preceding examples the octave is the highest part. But as the third or the fifth may also be the highest part, it follows that the perfect common chord admits of three positions, which are named according to the interval which occurs at the top or highest part. Ex.
