The oldest datable work is a chanson, _Resveillies vous et faites chiere lye_, written in honor of the marriage of Charles Malatesta, Lord of Pesaro, and Vittoria Colonna, in 1415. Dufay was one of the first composers to use the unfilled white notes, and it is believed that he introduced other changes in notation. He deserves great credit for discarding, in his later works, the empty fourths and fifths, as well as the parallel fifths, which still disfigured the music of some of the ablest composers of the early fifteenth century. We find, furthermore, in Dufay a more developed, though not very extended, canonic treatment of voices; and, again, there is occasionally noticeable a strong tendency toward expression, as, for example, in the mass, _Ecce Ancilla_, which is even more interesting on account of its harmonic character. Moreover, after he settled at Cambrai in 1436--that is, after Dunstable’s European fame was established--a new conception, similar to that found in the English composer’s works, seems to animate his compositions. His dry methods change, the different voices become more melodious, the harsher discords disappear, and the use of canon grows more frequent. The feature of Dufay’s epoch, however, which had a most far-reaching effect, and one which, incidentally, brought the wrath of fifteenth century critics upon his head, was the practice of using in the mass secular melodies in place of the Gregorian cantus firmus. For example, the folk songs, _Tant je me déduis_, _Se la face ay pale_, and _L’omme armé_, were incorporated as 'subjects’ in a number of masses, which were named after the tunes. The absolute invention of new subjects was foreign to composers of that day, and such familiar tunes, repeated in the various parts of the mass, supplied a familiar nucleus, while the composer’s ingenuity found ample play in weaving about it manifold figures and phrases. This was decidedly a new departure, and one that could not be agreeable to the Church. But the new fashion was no sooner set than other composers eagerly took it up. Dufay’s pupils adopted it and passed it on to the later Netherlanders, who in turn handed it down to the Romans. _L’omme armé_ became such a favorite for the mass that the younger Gallo-Belgians, Faugues and Caron, the Netherlanders Josquin and Lasso, and even the Roman Palestrina, in his early work, made use of it. In appropriating these secular melodies usually only the beginning was employed, and around this were woven contrapuntal devices. In this manner the new melody acquired almost the importance of a theme. Imitation of one part by another, at a greater or less interval of time, is, at present, so inevitably a characteristic feature of every musical composition of a higher order that it is difficult to imagine a time when it was far from being an obvious or necessary element. The invention of this art was for long attributed to Okeghem and his school; though it is now apparent that it was not only