Micrologus

Micrologus, Guido of Arezzo's own treatise on chant pedagogy, traditionally dated around 1026, is a primary medieval musical text describing the four line musical staff and the solmization syllables later called solfege, both innovations credited to Guido himself. Its authority is that of the originating author's own account of his own pedagogical method, foundational to the entire subsequent history of Western musical notation. Its limit is that, as an eleventh century pedagogical treatise, precise dating and some attribution details rest on manuscript transmission history rather than a single certain autograph. Cite it for the described innovations; a contested dating question needs a dedicated musicological study.