This essay examines the intellectual and aesthetic aspects of Luca Marenzio's "Madrigali a quattro, cinque et sei voci" (1588). By analysing the collection's letter of dedication - a condensed manifesto of musical poetics - initially I examine the cultural background of Mario Bevilacqua, the Veronese nobleman to whom the collection is addressed, assuming that he was involved in planning the book. Hence I explore the internal coherence of the collection which was conceived of as a unitary poetic and musical songbook, inspired by the dictates of the "mesto" ('sad') and "grave" ('heavy') styles. In the second part of the essay I highlight how this 'reservata' aesthetic choice derived from an awareness of a concept of style also shared by two other contemporary madrigal collections: one by Lasso and one by Monte, both dedicated to Bevilacqua. I also investigate how the "question of style" was connected to the way in which some codified precepts of classical rhetoric were received in the late humanistic period, particularly as regards the threefold division of styles into elevato (high), mediocre (medium) and umile (humble or low) often applied during the Sixteenth century also to the genres of secular vocal music.