CORNELL

CHAPTER IIISCALES— (a)MODAX, INFLUENCESIt is doubtful if there ever has been a reaUy fixed, stable, anddefinite scale. That the art has been, and stiU is worked outThe Three-°^®'' ^^ oscillating threefold basis, of which thefold Basis constituents are almost as diverse as the coloursof Music.j.gjj^ blue, and yellow, only adds to its ever-increasingcharm and vitality. This threefold basis is(a) The modal system.(6) The pure temperament.(c) The equal temperament.We have already referred to the tendency of the greatcomposers at times to modify the diatonic scales in thedirection of some of the modes. The modal influ-6^ce is as vital to-day as ever, but in a less pureStraltn ^s°and subtler way. The chromatic scale, in its turn,has constantly oscillated between a system of harmonyfounded on the pure temperament and one based on theequal tuning. With many modem composers the capitulationof the former to the latter is now entire, leaving a twelvenotesystem founded on a central Tonic.It is important to remember that any scale is a pureconvention, a thing which exists only in the imagination.No onepermanent" ^^^ system of scales, modes, and harmonic tissuesdoes not rest solely upon unalterable natural laws,but is at least partly the result of aesthetic principleswhich have already changed, and will still furtherchange with the progressive development of humanity"(Helmholtz, "The Sensation of Tone," chap. xii.). The influenceof the modes re-entered music as imperceptibly asthe modes have been temporarily obliterated formerly bythe more modern diatonic scales. The arbitrary use of the" Tierce de Picardie " chords, and such chords as that in the24