Hildegard gave every Virtue in Ordo Virtutum her own sung line, a compositional choice that was also a theological one: in her wider theology, music was the residue of the harmony Adam possessed in Eden and lost at the Fall, so that singing itself is a form of praise unavailable to fallen or rebellious beings. The Devil's part carries no melody at all. He shouts and declaims his lines while every other character, virtuous or merely human, sings, a staging choice scholars read as Hildegard making an argument about the nature of evil rather than merely a musical contrast: to Hildegard, harmony itself was evidence of divine order, and evil's defining trait was its exclusion from that order, its literal tonelessness.
The nuns of Hildegard's own convent performed the Virtues and the soul Anima, a female voice throughout, male clergy attached to the community sang the Patriarchs and Prophets who frame the action, and tradition holds that Volmar, Hildegard's provost and secretary, took the spoken role of the Devil himself. The play has drawn renewed performance and recording interest since the late twentieth century revival of interest in Hildegard's music generally, and modern stagings consistently preserve the spoken-versus-sung distinction as the work's most theologically loaded feature rather than treating it as a peculiarity to be smoothed over.