the successions of these concords and their alternations with
discord involved principles at once larger and more subtle than
those of mere difference in smoothness and artificiality. Not
only was a major chord (or at least its skeleton) necessary for
the final point of repose in a composition, but it could not itself
sound final unless the concords as well as the discords before it
showed a well-defined tendency towards it. This tendency was
best realized when the penultimate concord had its fundamental
note at the distance of a 5th or a 4th above or below that of the
final chord. When the fundamental note of the penultimate
chord is a 5th above or (what is the same thing) a 4th below
that of the final chord, we have an “authentic” or “perfect”
cadence, and the relation between the two chords is very clear.
While the contrast between them is well marked, they have one
note in common—for the root of the penultimate chord is the
5th of the final chord; and the statement of this common note,
first as an octave or unison and then as a 5th, expresses the
first facts of harmony with a force which the major 3rds of the
chords can only strengthen, while it also involves in the bass
that melodic interval of the 4th or the 5th which is now known
to be the germ of all melodic scales. The
relation of the final note of a scale with its
upper 5th or lower 4th thus becomes a
fundamental fact of complex harmonic significance—that is to
say, of harmony modified by melody in so far as it concerns the
succession of sounds as well as their simultaneous combination.
In our modern key-system the final note of the scale is called the
tonic, and the 5th above or 4th below it is the dominant. (In
the 16th century the term “dominant” has this meaning only
in the “authentic” modes other than the Phrygian, but as
an aesthetic fact it is present in all music, though the theory
here given would not have been intelligible to any composers
before the 18th century). Another penultimate chord asserts
itself as the converse of the dominant—namely, the chord of
which the root is a 5th below or a 4th above the final. This
chord has not that relationship to the final which the dominant
chord shows, for its fundamental note is not in the harmonic
series of the final. But the fundamental note of the final chord
is in its harmonic series, and in fact stands to it as the dominant
stands to the final. Thus the progression from subdominant,
as it is called, to tonic, or final, forms a full close known as the
“plagal cadence,” second only in importance to the “perfect”
or “authentic cadence.” In our modern
key-system these three chords, the tonic,
the dominant and the subdominant, form
a firm harmonic centre in reference to which all other chords are
grouped. The tonic is the final in which everything ultimately
resolves: the dominant stands on one side of it as a chord based
on the note harmonically most closely related to the tonic,
and the subdominant stands on the other side as the converse
and opposite of the dominant, weaker than the dominant because
not directly derived from the tonic. The other triads obtainable
from the notes of the scale are all minor, and of less importance;
and their relationship to each other and to the tonic is most
definite when they are so grouped that their basses rise and fall
in 4th and 5ths, because they then tend to imitate the relationship
between tonic, dominant and subdominant.
Here are the six common chords of the diatonic scale. The triad on the 7th degree or “leading-note” (B) is a discord, and is therefore not given here.
The submediant is so-called because if the subdominant is taken a 5th below the tonic, the submediant will come midway between it and the tonic, as the mediant comes midway between tonic and dominant.
Now, in the 16th century it was neither necessary nor desirable that chords should be grouped exclusively in this way. The relation between tonic, dominant and subdominant must necessarily appear at the final close, and in a lesser degree at subordinate points of repose; but, where no harmonies were dwelt on as stable and independent entities except the major and minor triads and their first inversions, a scheme in which these were confined to the illustration of their most elementary relationship would be intolerably monotonous. It is therefore neither surprising nor a sign of archaism that the tonality of modal music is from the modern point of view often very indefinite. On the contrary, the distinction between masterpieces and inferior works in the 16th century is nowhere more evident than in the expressive power of modal tonality, alike where it resembles and where it differs from modern. Nor is it too much to say that that expressive power is based on the modern sense of key, and that a description of modal tonality in terms of modern key will accurately represent the harmonic art of Palestrina and the other supreme masters, though it will have almost as little in common with 16th-century theory and inferior 16th-century practice as it has with modern custom. We must conceive modal harmony and tonality as a scheme in which voices move independently and melodiously in a scale capable of bearing the three chords of the tonic, dominant and subdominant, besides three other minor triads, but not under such restrictions of symmetrical rhythm and melodic design as will necessitate a confinement to schemes in which these three cardinal chords occupy a central position. The only stipulation is that the relationship of at least two cardinal chords shall appear at every full close. At other points the character and drift of the harmony is determined by quite a different principle—namely, that, the scale being conceived as indefinitely extended, the voices are agreed in selecting a particular section of it, the position of which determines not only the melodic character of each part but also the harmonic character of the whole, according to its greater or less remoteness from the scale in which major cardinal chords occupy a central position. Historically these modes were derived, with various errors and changes, from the purely melodic modes of the Greeks. Aesthetically they are systems of modern tonality adapted to conditions in which the range of harmony was the smallest possible, and the necessity for what we may conveniently call a clear and solid key-perspective incomparably slighter than that for variety within so narrow a range. We may thus regard modal harmony as an essentially modern scheme, presented to us in cross-sections of various degrees of obliquity, and modified at every close so as either to take us to a point of view in which we see the harmony symmetrically (as in those modes[1] of which the final chord is normally major, namely the Ionian, which is practically our major scale, the Mixolydian and the Lydian, which last is almost invariably turned into Ionian by the systematic flattening of its 4th degree) or else to transform the mode itself so that its own notes are flattened and sharpened into suitable final chords (as is necessary in those modes of which the triad on the final is normally minor, namely, the Dorian, Phrygian and Aeolian). In this way we may describe Mixolydian tonality as a harmonic scheme in which the keys of G major and C major are so combined that sometimes we feel that we are listening to harmony in C major that is disposed to overbalance towards the dominant, and sometimes that we are in G major with a pronounced leaning towards the subdominant. In the Dorian mode our sensations of tonality are more confused. We seem to be wandering through all the key-relationships of a minor tonic without defining anything, until at the final close the harmonies gather strength and bring us, perhaps with poetic surprise, to a close in D with a major chord. In the Phrygian mode the difficulty in forming the final close is such that classical Phrygian compositions actually end in what we feel to be a half-close, an impression which is by the great masters rendered perfectly artistic by the strong feeling that all such parts of the composition as do not owe their expression to the variety and inconstancy of their harmonic drift are on the dominant of A minor.
It cannot be too strongly insisted that the expression of modal music is a permanent artistic fact. Its refinements may be crowded out by the later tonality, in which the much greater
- ↑ See Plain Song.
