The revolution that has taken and is still taking place in music since the beginning of the 12th century is one of the most sudden and exciting revolutions in the history of any art. In its earliest origin music was conceived entirely from the point of view of counterpoint—the writing of one melody against another. The horizontal aspect was the only one possible in a time when the ancient modes were supreme: and to the present day almost all primitive music ignores the claims of harmony altogether. Even the combination of several melodies was not originally regarded by the Ancients as having a genuinely harmonic effect They were so concerned with the movements of the various parts in a horizontal direction that the perpendicular effect of the music was disregarded. After a while, however, it became clear that concerted music must be regarded from another aspect as well as from the purely contrapuntal : and composers began definitely to construct their concerted works on a harmonic basis, employing of course only the simplest concords at first. Experimenters were not lacking to expand the field of harmonic variety; and Monteverde horrified his contemporaries by the extraordinary freedom and boldness of his methods. Hitherto discords were known to all writers, but they had always been carefully prepared and as carefully resolved. Monteverde in his madrigals simply disregarded the accepted rules of counterpoint and used the diminished triad and the unprepared dissonances of the seventh and ninth. In the madrigal “Cruda Amarilli” examples of all these things are found.