28. A figured bass, or continuo, is the bass of a composition supplied with numerals indicating the chords to be filled in by the accompanist. Thorough-bass (Ger. Generalbass) is the art of interpreting such figures.
(D. F. T.)
[1] Musical intervals are reckoned numerically upwards along the degrees of the diatonic scales (described below). Intervals greater than an octave are called compound, and are referred to their simple forms, e.g. the 12th is a compound 5th.
[2] It is at least probable that this is one of the several rather obscure reasons for the peculiar instability of the 4th in modern harmony, which is not yet satisfactorily explained.
[3] The perfect concords are the octave, unison, 5th and 4th. Other diatonic combinations, whether concords or discords, are called imperfect.
[4] See [Plain Song].
[5] Until Beethoven developed the resources for a wider scheme of key-contrasts, the only keys for second subjects of sonata-movements were the dominant (when the tonic was major) and the “relative” major or dominant minor (when the tonic was minor). A wider range was possible only in the irresponsible style of D. Scarlatti.
[6] Many theorists mistake the usual extreme emphasis on the dominant chord of the dominant key, in preparation for second subjects, for a modulation to the major supertonic, but this can deceive no one with any sense of tonality. A good practical test is to see what becomes of such passages when translated into the minor mode. Illusory modulation to the flat 7th frequently occurs as a bold method of throwing strong emphasis on to the subdominant at the outset of a movement, as in Beethoven’s Sonata, Op. 31, No. 1.