At various points in the narratives of Chaucer's Book of the Duchess, Troilus and Criseyde, Canterbury Tales, Lydgate's Fall of Princes, and Henryson's Testament of Cresseid, protagonists or narrators express passionate feeling in the form of song, that is, in verse imagined to be musically performed, or at least marked by one or more formal features associated with song. And of course much medieval song – although by no means all of it – purports to express erotic and religious desire, joy, regret or complaint. But these later English poets seem to go further, implying that for them song is generically associated not only with the expression but also with the excitation of various kinds of feeling. By inserting emotionally expressive songs into their ethical, philosophical – and in varying degrees religious – tales, they use song to experiment with the possibility, and the problematics, of the passionate response.

This insertion inevitably encourages a theoretical reflection on the formal properties of song, including those that might make it a particularly effective means of expressing, exciting, and in some way containing, passion. These inserted songs are always, after all, marked or formally differentiated from the rest of the narrative; this is effected by means of narrative information (we may be told it is ‘sung’), by formal or metrical shape (often the text has a distinct song form), or by rubrication (in the English writers mentioned above inserted songs are variously described as song, lai, envoie, canticus, compleynt, or exclamatioun).