The acts of church councils offer us an exceptionally rich source of information about the utterances and behaviour of large numbers of bishops while engaged in one of their most important duties, namely the collective establishment of orthodoxy and the identification of heresy. They provide examples of Christian leaders in action, not only of individual bishops who in their own cities would be regarded as leaders but in the context of an ecumenical council were overshadowed by their metropolitans or the patriarchs or other key figures prominent in a particular debate, but also of a small number of international leaders. Although the absolute accuracy of council records is open to challenge, with the impossibility of verbatim precision, especially during heated moments, being acknowledged by those responsible for attempting to produce the records, the general impression of the tone and conduct of debates is beyond challenge, while the subscriptions by individual bishops to various decisions also offer insights into how the participants wished their involvement to be registered and remembered.

Episcopal behaviour has recently been the subject of two illuminating studies. The first, by Claudia Rapp, identifies different strands of episcopal authority – spiritual, ascetic and pragmatic –, probes how these were combined to legitimate that authority, and considers how bishops as men of power operated within the evolving economic and social structures of their cities.