Arguably few playgoers today are aware that Act 4 of Shakespeare's Romeo and Juliet ends with musicians engaging in badinage with a clown. Treated generally as superfluous or insignificant, the Peter and the Musicians scene is now cut more often than not. Yet Shakespeare must have had some larger dramatic purpose for it in mind, as the same musicians appear as spectators in the preceding "false lamentations" scene, where key characters mistakenly mourn Juliet's putative death. Too dramatically crucial to obliterate, this section too has nonetheless been redacted heavily and roundly criticized over the years, usually for the effusive, stilted, and formalized nature of its rhetoric. From an interdisciplinary perspective this paper reexamines these scenes as well as other moments in the play that feature musical allusions. It posits that Shakespeare used the musicians and other characters he thrust unawares into the act of "false lamentation" to portray the rhetorical trope of catachresis and that his model was O that most rare breast, a polyphonic song by the Elizabethan composer William Byrd. After purportedly composing O that for the funeral of the famous military hero and English sonneteer Sir Philip Sidney, Byrd used literary methods of sequential arrangement to develop an elaborate interdisciplinary tribute to his subject in his first published collection of English texted music. It was Byrd's venture into literary structures, via the rhetorical method of eristic imitation, I argue, that drew Shakespeare toward the song as he developed his hitherto unnoticed catachrestic conceit in Act 4 scene 5. Romeo and Juliet has long been associated with music. Byrd was the premier musician of Shakespeare's day and recent studies of Elizabethan rhetoric have been markedly interdisciplinary. This paper, nonetheless, will be the first to contend that Byrd and Shakespeare had any direct influence on one another. Shakespeare, it has long been argued, was so focused on the "lowly" popular ballad and the "lofty" theories of musica mundana that he took little interest in Byrd's specialty in "pricksong" (art song). Byrd's reputation, in turn, has long suffered from the idea that he was "unliterary." Recent studies, however, point a way out of this quagmire. Students of the so-called New Rhetoric have exposed ways in which Byrd might have approached the literature of his time that have not been considered or have been disregarded as Music and Shakespeare revisionists Joseph M. Ortiz, Erin Minear, and Andrew Mattison have opened new paths for interaction across disciplines in their findings that Shakespeare might "silence ... music" or provide "contexts that pull songs away from their musical status." From an interdisciplinary perspective gleaned from these approaches it will be shown not only that the scenes in Romeo and Juliet involving music were carefully integrated into the dramatic action, but also that they were integral to one of the play's larger purposes, which was to encourage an end to the enmity surrounding religious divisions of the time.