composers—­in setting, for instance, the words of the Mass—­took for a beginning a fragment of Church melody, or, to the great scandal of the ecclesiastics, secular melody.  Call this bit A, and say it was sung by Voice I.; Voice II. took it up in a different key, Voice I. continuing with something fresh; then Voice III. took it in turn, Voices I. and II. continuing either with entirely fresh matter, or Voice II. following in the steps of Voice I. And so on, either until the whole piece was complete or a section ended; but the end of one section was the jumping-off place for the commencement of another, which was spun out in exactly the same way.  This method of “imitation” was employed by all the polyphonic composers.  Continuity was assured; lovely or unlovely harmonic dissonances were always arising, and being resolved through the collisions and onward movement of parts; the music, both melodically and harmonically, could be as expressive as the particular composer’s powers allowed.  But the unity was the unity of a number of pieces of wood of varying length laid so as to overlap and nailed together; the superficial unity was due to the words; the real, essential unity depended on all the music being the sincere expression of a steady emotion—­in those days religious emotion.  Thus were attained the motet forms and the Mass, and, when the method was applied to secular words, the madrigal.

The earlier instrumental pieces were built after the same fashion—­see the “fancies” and organ compositions of the time; but in these there were no words either to give the impulse or hold the bits together.  With the fugue, music, unaided by words, was held together by its own innate strength; it became a self-sustaining One subject was generally taken; others—­oftenest one, sometimes more—­were added; all the subjects were passed about from part to part until the end of the composition, with the interspersion of passages called “episodes” for the sake of “variety.”  Here there was unity, continuity, with a vengeance.  It was of the very essence of the fugue that the motion should never be arrested; if it seemed to halt for a moment, then, as in the older music, the stopping-place was the jumping-off place for a fresh start.  All the severer men wrote in this form, most of them displaying marvellous mathematical—­and some of them, alas! mechanical—­ingenuity; a few of them, Bach towering high above the rest, attained a full and truthful expression of deep feeling.  Bach, for the organ alone, raised sublime architectural structures, unapproachable, to use Schumann’s word, in their magnificence.  But the underlying feeling was always the same throughout; it might wax or wane in intensity:  its character did not change.  The themes, once announced, were rigid and unalterable; the music had always to be more or less like “a tune tied to a post.”  Dramatic changes of mood had no place.  So later, a voice had to be found for shifting, complex, theatrically conflicting