In the 2nd scene of the and act of 'Tristan and Isolde' the combination given theoretically above (p. 679a) actually occurs, and two of the preliminary chromatic notes (*) are sustained as a suspension into the next chord—
In the latter part of the last Act of the same work are some extremely remarkable examples of the adaptation of the polyphonic principle to harmony, entailing very close modulations, for which there is not space here.
The principle of persistence was early recognised in the use of what were called Diatonic successions or sequences. They are defined by Prof. Macfarren as 'the repetition of a progression of harmony, upon other notes of the scale, when all the parts proceed by the same degrees in each repetition as in the original progression,' irrespective of augmented or diminished intervals, or doublings of notes which in other cases it is not desirable to double. And this may be expanded into the more general proposition that when a figure has been established, and the principle and manner of its repetition, it may be repeated analogously without any consideration of the resulting circumstances. Thus Beethoven having established the form of his accompaniment—
goes through with it in despite of the consecutive fifths which result—
Again, a single note whose stationary character has been established in harmony of which it actually forms a part, can persist through harmonies which are otherwise alien to it, and irrespective of any degree of dissonance which results. This was early seen in the use of a Pedal, and as that was its earliest form (being the immediate descendant of the Drone bass mentioned at the beginning of the Article) the singular name of an inverted Pedal was applied to it when the persistent note was in the treble, as in an often-quoted instance from the slow movement of the C-minor Symphony of Beethoven, and a fine example in the Fugue which stands as Finale to Brahms's set of Variations on a Theme by Handel, and in the example quoted from Purcell's Service above. Beethoven even makes more than one note persist, as in the first variation on the Diabelli Valse (op. 121)—
Another familiar example of persistence is persistence of direction, as it is a well-known device to make parts which are progressing in opposite directions persist in doing so irrespective of the combinations which result. For the limitations which may be put on these devices reference must be made to the regular text-books, as they are many of them principles of expediency and custom, and many of them depend on laws of melodic progression, the consideration of which it is necessary to leave to its own particular head.
It appears then, finally, that the actual basis of harmonic music is extremely limited, consisting of concords and their inversions, and at best not more than a few minor sevenths and major and minor ninths; and on this basis the art of modern music is constructed by devices and principles which are either intellectually conceived or are the fruit of highly developed musical instinct, which is according to vulgar phrase 'inspired,' and thereby discovers truths at a single leap which the rest of the world recognise as evidently the result of so complex a generalisation that they are unable to imagine how it was done, and therefore apply to it the useful term 'inspiration.' But in every case, if a novelty is sound, it must answer to verification, and the verification is to be obtained only by intellectual analysis, which in fact may not at first be able to cope with it. Finally, everything is admissible which is intellectually verifiable, and what is inadmissible is so relatively only. For instance, in the large majority of cases, the simultaneous occurrence of all the diatonic notes of the scale would be quite inadmissible, but composers have shown how it can be done, and there is no reason why some other composer should not show how all the chromatic notes can be added also; and if the principles by which he arrived at the combination stand the ultimate test of analysis, musicians must bow and acknowledge his right to the combination. The history of harmony is the history of ever-increasing richness of combination, from the use, first, of simple consonances, then of consonances superimposed on one another, which we call common chords, and of a few simple discords simply contrived; then of a system of classification of these concords and discords by key relationship, which enables some of them to be used with greater freedom than formerly; then of the use of combinations which were specially familiar as analogues to essential chords; then of enlargement of the bounds of the keys, so that a greater number and variety of chords could be used in relation to one another, and finally of the recognition of the principle that harmony is the result of combined