Some of the elements of the Chromatic System were known 200 years ago. The Diatonic scale, being called the "Natural scale," implied that the chromatic chords were consider to be artificial; but the notes of the chromatic chords, from their PROXIMITY to the notes of the tonic chord, fit to them like hand and glove. Nothing in music is more sweetly natural and pleasingly effective than such resolutions; and hence their extensive use in the hands of the Masters. The chromatic chords have close relations to the whole system of music, making the progressions of its harmonies easy and delectable, and producing effects often enchanting and elevating, as well as often subtle and profound; and while they are ever at hand at the call of the Composer, they are ever in loyal obedience to the laws of their own structure and system. When a diatonic chord precedes another diatonic chord belonging to the same scale, it has one note moving in semitonic progression;1 but when a chromatic chord precedes a diatonic chord, it may have three semitonic progressions.2 The primary chromatic chord resolves into 8 of the 24 diatonic tonic chords, with 3 semitonic progressions. These identical notes of the chromatic chord, with only some changes of names, resolve into another 8 of the 24 tonic chords, with 2 semitonic progressions and one note in common; and when they resolve into the third and last 8 of the 24 tonic chords, they move with one semitonic progression and 2 notes in common. So to the chromatic chord there are no foreign keys.3 And as it is with the first chromatic chord, so with the other two. [Scientific Basis and Build of Music, page 51]
That some of the elements of the Chromatic System were known 200 years ago, but have been known so long without being formed into a system, shows that what was known and in use of chromatic chords had been found out from experience, and not from any knowledge of the laws which generate and constitute them. Without the knowledge of these laws they could not be explained; and this accounts for the entire want of order in everything which relates to them, and for the names which been applied to those which are in use, such as "the minor ninth," "the diminished seventh," "the extreme sharp second," etc. One chromatic chord has all these things in it, but it does [Scientific Basis and Build of Music, page 51]
1 See Plate XI.
2 See Plates XVII. and XVIII.
3 For illustration of this passage see Plates XIX. and XX.
See Also