Edward Berdoe,
The Browning Cyclopædia: A Guide to the Study of the Works of Robert Browning
“ The ‘commiserating sevenths’ are closely connected with the ‘dominant’s persistence’ in the next verse:—‘Hark! the dominant’s persistence till it must be answered to: So an octave struck the answer.’The dominant chord in music is the chord written on the fifth degree of the scale, and it almost always has a seventh added to it, and in a large percentage of cases is followed by the tonic, the chord on the first degree of the scale. Now, in fugue form a theme is repeated in the dominant key, the latter being called the answer. ”
