In 1787 he moved to Naples, where he lectured in the Humanities, came into contact with Enlightenment thinkers (Gaetano Filangieri, Mario Pagano, Antonio Jerocades, Nicola Pacifico and others), and progressively distanced himself from the Church.
In 1788, when Ferdinand IV of Naples refused to pay the annual tribute of the Chinèa to the Pope, Salfi wrote a satire against the Papal States and in praise of the Neapolitan government.
In the same year, Salfi joined the newly founded Neapolitan Patriotic Society, a Masonic lodge modelled on the Jacobin Club, whose members were planning a violent insurrection.
The conspiracy was discovered and in 1794, to avoid a trial, Salfi escaped from Naples to Genoa, where he quit the priesthood, and then to Milan, where he shortened his name to "Franco" and actively collaborated with the Republican newspaper Lombardy's Political Thermometer.
[4] As a poet, Salfi composed lyrics on Napoleon, a free-verse poem on the lynching of Hugou de Basseville (in a dispute with Monti), as well as some tragedies inspired by Alfieri (such as Virginia bresciana in 1797, Pausania in 1801) and many librettos.