Dante assumes that poems will be set to music. Canzoni are poems that might be set to music, whether they are actually set to music or not. Earlier he defines poetry as verbal inventions obeying the rules of rhetoric and music. We cannot call it a song unless it has words:
"Furthermore, we must now discuss whether the word canzone should be used to refer to a composition made up of words arranged with due regard to harmony, or simply to a piece of music. To which I answer that a piece of music as such is never given the name canzone, but is rather called 'sound', or 'tone', or 'note', or 'melody'. For no player of a wind or key- board or stringed instrument ever calls his melody a canzone, except when it is wedded to a real canzone; but those who harmonise words call their works canzoni, and even when we see such words written down on the page, in the absence of any performer, we call them canzoni. And so it seems clear that the canzone is nothing else than the self-contained action of one who writes harmonious words to be set to music; and so I shall assert that not only the canzoni we are discussing here, but also ballate and sonnets and all arrangements of words, of whatever kind, that are based on harmony, whether in the vernacular or in the regulated language, should be called canzoni."