 Until 1815, the only extant works ascribed (erroneously) to Fronto were two grammatical treatises, "De nominum verborumque differentiis" and "Exempla elocutionum" (the latter being really by Arusianus Messius).In that year, Angelo Mai discovered in the Ambrosian library at Milan a palimpsest manuscript, on which had been originally written some of Fronto's letters to his imperial pupils and their replies; four years later Mai found several more sheets from this manuscript in the Vatican.These palimpsests had originally belonged to the famous convent of St Columbanus at Bobbio, and had been written over by the monks with the acts of the First Council of Chalcedon.