Accent and Accent-Marking in Ancient Greek
The practice of marking accents was initiated by literary scholars in Alexandria ca. 200 B.C.E. Accent marking was needed to help in the correct pronunciation of unfamiliar words in the great poetry of the past, to eliminate ambiguities that would be present in an unaccented text lacking word division, to help in dealing with divergences in dialects, and perhaps to facilitate the teaching of Greek to foreigners.
Extract of an image of an ancient book-roll (papyrus) of the late 1st cent. BCE or early 1st cent. CE