[Illustration]

And anyone can try for himself on a piano, and find out that this chord
makes the longing for the tonic chord--the chord of C--more imperious
and the feeling of rest satisfying in proportion when the last chord is
reached. That was one step: the next was to convert the dominant, G, of
the key of C into a tonic for the time being, to get a sense of having
reached the key of G. That was done by regarding G as a tonic, and on
_its_ dominant, D, writing a chord, either a dominant seventh or a
simple major common chord, leading to a chord of G--thus:

[Illustration]

But if after this a seventh on the dominant is played, followed by the
original key-chord

[Illustration]

then we are home once more in the original key. If the reader will
imagine, instead of a few simple chords, a passage of music in the key
of C, followed by a passage in the dominant key of G, and ending with a
passage in the key of C, he will perceive that here is the deep
underlying principle of modern music: that after a certain length of
time spent in one key the ear wearies, and the modulation to the new key
is grateful; but after a time the ear craves for the original key again,
so after getting to that, and spending a certain time there, a piece
closes with perfectly satisfying effect. Haydn was the first to get that
principle in an iron grasp and use it, with numberless other devices, to
get unity in variety. Not till nearly a hundred years after Purcell's