Agency and agentive prepositions in Late Latin

I propose the results of an analysis whose object is the expression of the Agent by means of a prepositional phrase in Post-Classical and Late Latin passive constructions. My interest comprises both the prepositions used in Latin to encode the passive Agent (namely ab), and those constituting the bases for the development in the Romance languages (namely per and de). The analysis is based on the functional approach to Transitivity proposed by Hopper and Thompson 1980 and on Cognitive Grammar, specifically on Langaker 1991 and the various Luraghi’s works on prepositions and cases in ancient Indo-European languages.