Thesis (Ph. D.)--Catholic University of America, 1942. / "Select bibliography": p. xiii-xv.

This dissertation investigates how two fifth-century bishops of Rome, Leo I (440-461) and Gelasius (492-496) understood and opposed heresy. More specifically, by stressing the contested character of heresy and the at times optative nature of the bishop of Rome’s opposition to it, this dissertation hopes to provide a new perspective on how Leo and Gelasius imagined and justified the authority of the Apostolic See in an uncertain world. To accomplish this task, this dissertation considers Leo and Gelasius’ opposition to various different heresies and details the methods by which they were opposed. This will be done through an examination of the records of synods, Roman law, other contemporary narrative sources, but especially through the letters and tractates of Leo and Gelasius themselves, carefully read and considered in their fifth-century context. Furthermore, it is argued that the history of the development of the ideas of heresy and orthodoxy were profoundly connected with Rome’s emerging importance as a locus of authentic Christian teachings; the history of the bishops of Rome cannot be told without examining the history of heresy and orthodoxy and vice versa. Because orthodoxy and heresy were not tangible historical phenomena but rather were malleable categories that emerged as part of a wider discourse of Christian identity construction, the bishops of Rome were not in every case the unqualified enemies of heresy. Instead, their definition of heterodox belief and their opposition to religious deviance were complex, often qualified and always historically contingent. This study seeks to investigate the way in which Leo and Gelasius mobilized the language of heresiology in order to convince Christians in the Latin west and the Greek east, as well as the imperial authorities, that Rome’s interpretations were legitimate and binding.