Firmilian (d. 268 CE), a well-known bishop of the Cappadocian metropolis Caesarea (from c. 230 CE), appears according to Eusebius of Caesarea (Hist. eccl. 6.27) to have taken part in almost all of the significant debates in the formation of una sancta et catholica ecclesia (one holy and catholic church) and its standardized structures in the middle of the 3rd century CE as a representative of an episcopally organized church. The institution of synods and intensive epistolary communication between the churches appear to be for him a fundamental element in the structure of the ecclesia cat…