largely unconscious result of certain accidents that may occur in unison monophonic singing; it is certainly not surprising that during the later Middle Ages polyphony should be so deeply rooted in what are essentially monophonic attitudes that people of the modern world find it, at first at least, curiously difficult of approach. We know more or less what we expect from music conceived in “parts”, and the mediaeval composer does not gratify our expectations. But before we dismiss him as ‘primitive’ or ‘tentative’ we ought to be sure that we understand what he thought he was trying to do. He was not really trying to break with the implications of the monophonic music on which he had been nurtured and which, as we have seen, symbolized the philosophy inherent in his world; he was perhaps trying to extend that music’s resources, and in so doing he quite unwittingly introduced