If we try to outline in the roughest way the half dozen or so most important schools we can find in the entire history of music we shall get something like the following. After the long groping among the rudiments that went on through Greek and early Christian times there emerged during the middle ages a type of ecclesiastical music which, after a development of several centuries, culminated in the work of Orlando de Lasso (1520-1594), Giovanni Pierluigi da Palestrina (1524-1594), and others. This music is as primitive, archaic, and severe to our ears as the early Flemish religious pictures are to our eyes. It can be described chiefly in negatives. It did not employ instruments, but only voices in the chorus. It had no regular time-measure, but wandered on with as little definiteness of rhythm as the Latin prose to which it was set. It employed no grating harsh combinations of tones ('dissonances’) such as make our music so stirring to the emotions, partly because they are difficult for voices, partly because the science of harmony was in its infancy, partly because the kind of expression it aimed at was that of religious peace. Each group of voices had its own melody to carry, and as there were sometimes as many as sixteen groups an extraordinarily complex web of voices or 'parts’ was developed, to which is due the name of polyphonic (many-voiced) applied to this school. Unsuited as it is to the restless temper of the modern man, it often attained within its own limits an exquisite beauty. With the application of this general type of art, the polyphonic, to instruments, especially the organ, new developments supervened. Dissonances were perfectly easy, and most effective, on the organ, that would have been impossible for voices. Definite metre and rhythm were gradually introduced. Above all, the many melodies of the older style to some extent gave way to the massive detached chords more suitable to the organ (because the player could grasp them by handfuls instead of having to make his fingers play hide and seek among the keys), and thus was born another great type of style, the 'homophonic’ (one main melody, accompanied by chords rather than by other melodies). At the same time the intellectual interest was vastly increased by the use of more and more definite and recognizable bits of melody, happily called the 'subjects’ or 'themes’ of the composition, which could be developed and marshalled just as a writer develops and marshals his thoughts. The fugue is the arch type of this kind of composition, with its style partly polyphonic and partly homophonic, its deep thoughtfulness, its ingenuity, and its surprising variety and depth of emotional expression. Its supreme master was Johann Sebastian Bach (1685-1750).