Temperate trueness is defective from many points of view. This is the universal opinion, but we are forced to accept this method by the absolute impossibility of any improvement, especially with the key-board instruments now in vogue; and it must be accepted until some new invention shall revolutionize the piano by modulating its tones, a transformation which would give that instrument not only the musical design, but also the color and warmth which it now lacks.
Let us pass to passional trueness, leaving science to enter the domain of art. "Passional trueness," said Delsarte, "consists in giving each semitone three, four, five, six, or even seven commas, according to its tendency." As we see, the precept is daring, and an inattentive scholar would only have to forget the last words of the definition to make people say that the great master of lyric art taught his pupils to sing false.
Every rule has its reason and its consequences. St. Augustine, who knew the Beautiful, of which art is only the expression, and who could explain it well, has given us a brief but admirable definition of music: "Music is a succession of sounds each calling forth the other." Simple yet profound words! The sounds call each other forth, desire and mutually attract each other, and in every age this attraction has been so clearly evident, that the seventh note in the scale, when it meets the others each of which has its particular name relating to its particular function, tonic, dominant, etc., is simply called the sensitive note, from its tendency to pass into the atonic.
Passional trueness is based upon this tendency of the notes to pass into those which succeed them, and upon this reciprocal attraction of sounds. Thus, notes, which have a tendency toward the acute or shrill, may be raised two commas or more above temperate trueness. Notes which have a tendency toward the grave may be lowered in the same proportion. (Example, taken from "The Prophet," by Meyerbeer.)
Here, the B may be but two commas distant from the C; and in the second example given, the A flat may also be but two commas removed from the G, and this change far from producing a disagreeable effect upon the ear, will make a most striking impression and the accent will be far more dramatic than before. Try the reverse, that is, divide the interval B sharp-C into seven commas on the semitones A flat-G; it will be unendurable. Whence we may deduce the fact that to sing false is to sing above or below a note in the inverse direction to its attraction.
Delsarte, in his definition, speaks only of the semitone, and we ourselves give examples of that sort of attraction only; but it does not follow that the other intervals are not equally subject to the same law. Their attraction may not be shown by the same effects.
The master added, in speaking of trueness in singing: "The triad is the breathing-place of the tonality; the notes composing it should be absolutely true. They are the singer's invariable and necessary law. They characterize repose. Their office is that of attraction, and they can only be attracted mutually, with the exception of the tonic, which is the centre of attraction not only for various notes, but for the phrase and the entire composition."