Next to nothing is known about his life but what can be inferred by the treatise itself. For a time he was a member of the monastery at St Jean de Réôme, in the Côte-d'Or near the present-day town of Moutiers-St-Jean. Aurelian said in his treatise that he was a former monk of Réôme, but had been dismissed from the community for an unspecified offense; he wrote the treatise as a form of penance, both at the request of his colleagues who needed his specialized knowledge, and as an attempt to supplicate Abbot Bernard of St Jean de Réôme; whether or not he was admitted back into the monastery as a result of his writing is not known. There is a record of an abbot named Bernard at St Jean de Réôme beginning in 846, who shortly afterward became bishop of Autun; this has helped establish the date for the treatise.
The Musica disciplina is the earliest writing on music from medieval Europe, in any language, since classical antiquity. Only Isidore of Seville wrote on music before Aurelian, and his subject was the music of antiquity. Aurelian's work is the first to cover plainchant, in the period immediately after Gregorian chant became standardized in northern and western Europe, and it also has the earliest extant sample of musical notation, although the particular notational scheme he used has so far resisted definitive interpretation, and it only appears in one small section of his book.
One of the most important topics covered in the Musica disciplina, to contemporary scholars, is the eight Tones, what are today known as the church modes, although Aurelian did not use the term. As sources, Aurelian used Isidore of Seville, Cassiodorus, and above all Boethius, but the eight Tones were more likely than not imported from Byzantine music in the 8th century. Instead of giving the modes the names used by the ancient Greeks as well as Boethius (Dorian, Phrygian, etc.) he invented his own names, such as noannoeane, and noeagis; he also includes the fascinating bit that Charlemagne himself had commanded that four more Tones be added to the existing eight, making a total of twelve (it would not be until the 16th century that the remaining four modes were again defined; this occurred in the Dodecachordon of Heinrich Glarean).
A current matter of controversy is whether the Musica disciplina is a survival of a tradition of writing on music, the rest of which has been lost, or whether Aurelian was the first to attempt to codify the existing practice. Music as an intellectual discipline had only been revived in the late 8th century by Alcuin, as part of a campaign to revive all of the liberal arts of antiquity, and which was one of the most significant features of the Carolingian Renaissance. There may have been prior, lost works on music from the late 8th and early 9th centuries; but if so, Aurelian makes no reference to them. In addition, Aurelian made many mistakes interpreting Boethius; European music theory was in its infancy, and the music theory of antiquity, as passed down by Boethius, was evidently difficult to understand and apply to the tradition of chant, which was the only music Aurelian knew.
Other topics covered in the Musica disciplina include the "music of the spheres," the ethical and moral effects of music, and musical proportions; in addition he includes a narrative about the inventors of music, for example Pythagoras and Jubal.
The book also contains descriptions of more than 100 chants; unfortunately they are verbal descriptions only, since pitch-specific notation had not developed by 850, although there have been several attempts to transcribe them and correlate them with later versions of the same chants.