"The inception of the principle of tonality and certain of its techniques expressing themselves in the construction of tonal units of various length and complexity goes as far back as the Organa of St. Martial and Santiago de Compostela. A continuous development of structural polyphony from the twelfth to the twentieth century may with justification be assumed. Whether we encounter the use of modes or the major-minor system, whether the contrapuntal voice voice leadings are different from those of later periods or whether harmonic thinking expresses itself in a different manner than later on in the eighteenth century, the music of the Middle Ages and Renaissance demonstrates the same basic principles of direction, continuity and coherence as music from the Baroque period to the twentieth century."