Aristophanes of Byzantium is credited with inventing the signs for Greek accents, breathings and vowel lengths, according to a single source: a short text found in two 16th-century Paris manuscripts. The passage has a doubtful history, but the story it tells is of considerable interest. We first provide a new edition of this text, based on a new examination of both manuscripts, and a complete translation. Secondly we argue that the author consulted a source that was in Latin and that dealt at least in part with the Latin accent. We conclude by considering the implications of our proposal for the text’s date and circumstances of composition.