O Livoris Feritas (O Savegness of Envy) is a Latin setting of a text written by the famed 14th Century composer/poet Guillaume de Machaut. Widely know for his musical contributions to the Ars Nova movement, Machaut also wrote many poems and narrative texts. This particular text first appears in his own motet setting of the same name. Here, the setting is an ominous one for unaccompanied male voices, where improvisational elements, vocal glissandi, and composed material are fused together to create a singular identity to the piece, while illuminating the near frightening character of the text.