 The philosopher Anicius Manlius Severinus Boethius (c. 480–525/26), normally referred to simply as Boethius, had a fundamental role in shaping medieval musical thinking. Through commentated translations of Greek authors and original expositions of their views, Boethius allowed classical Greek philosophical ideas to survive into the Middle Ages. He did so in the field of music by writing De Institutione Musica. In this work, Boethius summarizes music theory as found in the Greek treatises he knew. The book also distinguishes between three types of music: musica mundana, humana, and instrumentalis. Musica mundana is the harmony of the cosmos, a Pythagorean concept that found widespread acceptance over the course of the Middle Ages, though it was recast in Christian terms. Musica humana is described only briefly by Boethius, though it is clear that it is the harmony between the various elements that compose the human body. Some modern accounts of Boethius’s thought identify musica humana with singing, but this is incorrect, though it is true that later medieval thinkers used the term in such a way (see Dyer 2007: 59; 64; 69). Finally, musica instrumentalis is sounding music, vocal and instrumental. While this is undoubtedly regarded today as the core of music, Boethius considers it as music only in a derivative sense. Boethius’s tripartite division is repeated and accepted by numerous medieval writers on music.