When a number of parts came to be used together, the need of fixing the pitch and length of notes with precision became imperative. So out of the antique mnemonic signs, which had done useful service during the exclusive régime of the unison chant, there was gradually developed a system of square-headed notes, together with a staff of lines and spaces. But instead of simplicity a bewildering complexity reigned for centuries. Many clefs were used, shifting their place on the staff in order to keep the notes within the lines; subtleties, many and deep, were introduced, and the matter of rhythm, key relations, contrapuntal structure, and method of singing became a thing abstruse and recondite. Composition was more like algebraic calculation than free art; symbolisms of trinity and unity, of perfect and imperfect, were entangled in the notation, to the delight of the ingenious monkish intellect and the despair of the neophyte and the modern student of mediaeval manuscripts. Progress was slowest at the beginning. It seemed an interminable task to learn to put a number of parts together with any degree of ease, and for many generations after it was first attempted the results were harsh and uncouth. Even taking into account the obstacles to rapid development which exist in the very nature of music as the most abstract of the arts, it seems difficult to understand why it should have been so long in acquiring beauty and expression. There was a shorter way to both, but the church musicians would not take it. All around them bloomed a rich verdure of graceful expressive melody in the song and instrumental play of the common people. But the monkish musicians and choristers scorned to follow the lead of anything so artless and obvious. In a scholastic age they were musical scholastics; subtilty and fine pedantic distinctions were their pride. They had become infatuated with the formal and technical, and they seemed indifferent to the claims of the natural and simple while carried away by a passion for intricate structural problems.