Several points of intersection exist between vocal and instrumental music by Italian composers of the early seventeenth century. First, like books of vocal monody with an overt pedagogical purpose, volumes of instrumental music may have been designed to instruct the performer in the conventions of the modern style. Specifically, many books published in the 1610s and '20s offer their users a window on the changeable, fluid idiom of the stile moderno, in which contrast of musical material and a posture of invention assumes primary importance. Second, as in recitative and other vocal styles, much of the vocal and instrumental music of the early seventeenth century is dominated by a metrical flexibility that similarly contributes to an air of immediacy, and that seems designed to highlight the emotional qualities of the music--to convey and move the affetti . And third, whereas the theatrical nature of vocal music of the period--especially music destined for the stage--may appear obvious, some instrumental music of the period may be equally theatrical, containing instructions for interaction with an audience, staging, imitation, and role-play. These points of intersection in particular suggest a relationship between the instrumental stile moderno and the vocal stile rappresentativo, prevalent in operas, ensemble madrigals, and solo songs in the early 1600s. Although no single, exclusive definition of the stile rappresentativo exists, it is nevertheless possible to trace a constellation of features associated with that term through a variety of works. Despite the divergence of the specific musical language of the vocal and instrumental repertoires, some of the vocal features are analogous to elements of instrumental music discussed in the article
