Haydn found music in the eighteenth-century stage, and carried it on to the nineteenth-century stage--in some respects a very advanced nineteenth-century stage. The problem he had to solve was as easy as that set by Columbus to the wiseacres, when once it was worked. It was how to combine organic unity of form and continuity with dramatic variety and the expressiveness of simple heartfelt song. From the date of the invention of music written and sung in parts, a similar problem had been set successive generations of musicians, and solved by each according to its needs and lights. At first words were indispensable; they were, if not the backbone of the music, at least the string on which the pearls might be strung. The first veritable 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.