Didymus the Musician in Wikipedia
Didymus the Musician was a music theorist in Alexandria of the 1st century AD who combined elements of earlier theoretical approaches with an appreciation of the aspect of performance. According to Andrew Barker, his intention was to revive and produce contemporary performances of the music of Greek antiquity. The syntonic comma of 81/80 is sometimes called the comma of Didymus after him.
Among his works was On the Difference between the Aristoxenians and the Pythagoreans (Περὶ τῆς διαφορᾶς τῶν Ἀριστοχενείων τε καὶ Πυθαγορείων).