Diacritical marks introduced by Pietro Bembo with the help of his editor, Aldus Manutius, in the first edition of his dialogue De Aetna form a complex and well-structured system. Although devised for practical purposes, so as to ensure a correct reading and phrasing of the Latin text, this system is clearly based on solid theoretical premises. The decisive factor for its introduction was the experience of editing Greek texts, which became the impulse as well as the basis for the system of diacritical signs. The influence of Latin grammarians (in particular, Servius and Priscianus), who had applied Greek accent theory to Latin language, also played an important part. Within a system essentially devoid of ambiguity, the three accents conveyed a variety of indications bearing on the correct pronunciation of the text, from basic principles to expressive nuances. Several editorial decisions involving phrase accents suggest that Bembo considered not only private reading, whether oral or mental (endophasic), but also public declamation.