The propositions which must now be laid down are these: First, the choral parts of the work were in the form of the Italian frottola, and the final one may have approached more closely to the particular style of the canto carnascialesco (carnival song) and was certainly a ballata, or dance song. Second, the solo parts were constructed according to the method developed by the lutenists, who devised a manner of singing one part of a polyphonic composition and utilizing the other parts as the instrumental support. Third, there were two obligato instruments, the pipe used in the duet of the two shepherds, and the "lira" played by Orpheus. Fourth, there was probably an instrumental accompaniment, at least to the choral parts. In regard to the choruses, then, we must bear in mind the well established characteristics of the madrigal dramas of the sixteenth century. In these works the choruses were set to music in the madrigal style and they were frequently of great beauty. But the Italian madrigal had not been well developed at the time of the production of Poliziano's "Orfeo," while the frottola was the most popular song of the people. The frottola was a secular song, written in polyphonic style. The polyphony was simple and the aim of the composition was popularity. It is essential for us to bear in mind the fact that in the fifteenth century the cultivation of part singing was ardent and widespread. The ability to sing music written in harmonized form was not confined to the educated classes. It extended through all walks of life, and while the most elaborate compositions of the famous masters were beyond the powers of the people, the lighter and more facile pieces were readily sung.[22] [Footnote 22: "During the fifteenth century the love of part-singing seems to have taken hold of all phases of society in the Netherlands; princes and people, corporate bodies, both lay and clerical, vying with each other in the formation of choral societies." Naumann, "History of Music," Vol. I, p. 318. "The practice of concerted singing was not confined to the social circles of the dilettanti, but was also very popular in the army; and we have before alluded to the fact that Antoine Busnois and numerous others followed Charles the Bold into the field." Ibid., p. 320.]