How should one talk about the Roman emperor? How should one address him? For people living in the Roman Empire, these questions were far less trivial than they may seem at first glance. An example from Asia Minor serves to illustrate: when the people of the Phrygian city of Hierapolis decided to honour Antoninus Pius with a statue sometime during his reign, the emperor's titulature on the statue base included the designation ‘lord of the earth and the sea’. The original wording γῆς καὶ θαλάσσης δεσπότης was later changed by replacing δεσπότης with (probably) κύριος, a word that was considered more moderate and less harsh in expressing the emperor's position around the middle of the second century c.e. (SEG LIII 1463; see also T. Ritti, Storia e istituzioni di Hierapolis (2017), 425–6). Although there was an official form in the nomenclature of Roman emperors, known from administrative documents like imperial letters or military diplomas, there is plenty of evidence that subjects addressed emperors with formulations not present in the official imperial language, mostly by using honorary expressions that formed the so-called unofficial titulature of Roman emperors. It is in the very nature of things that the unofficial titulature of Roman emperors had generally a somewhat experimental character, and sometimes attempts to address the emperor were subsequently perceived as inappropriate for one reason or another, as in the case of the inscription from Hierapolis. One of the numerous merits of the book under review, Sophia Bönisch-Meyer's Dialogangebote, is its demonstration that the use of such formulations was subject to change over time. Some decades later, in the time of the Severans, applying the formulation γῆς καὶ θαλάσσης δεσπότης to Roman emperors had become a widespread practice in the Greek East of the Roman empire.

It might come as surprise that there has been less systematic analysis of the unofficial titulature of Roman emperors than one would expect. In studies of Roman emperorship, a top-down perspective has been counterbalanced by a bottom-up approach that has become increasingly relevant over the last three decades or so. Studies of perceptions and constructions of the emperors by their subjects are today no less important than those of the emperors’ forms of self-fashioning towards the various groups of the empire's population, not least because current scholarship considers the self-representation of Roman emperors as either anticipating or reacting to the expectations of the addressees. Thus, B.-M.'s massive study on the unofficial imperial titulature from Augustus to Severus Alexander is a highly necessary and most welcome contribution to scholarship and resolves a true desideratum.

The book, originating in a Heidelberg doctoral thesis, is divided into three principal chapters (84–418), preceded by a long introduction (1–83) and followed by short conclusions (419–22). The nondescript heading ‘Appendix: Tabellen 1–4’ conceals a major resource for ancient historians working on Roman emperors: in four tables extending over more than 100 pages (423–536), B.-M. catalogues the literary, epigraphic, numismatic and papyrological evidence for the unofficial titulature of each Roman emperor in the period under consideration. A comprehensive bibliography (537–65) and a detailed index (566–625) conclude this invaluable study.

This contribution, resting upon a meticulous collection and careful analysis of the evidence, is well structured. The three major chapters (‘Inoffizielle Epitheta in diachroner Perspektive’, 84–208; ‘Inoffizielle Epitheta im thematischen, medialen und funktionalen Kontext’, 209–319; ‘Handlungsakteure’, 320–418), focus on the evidence, its contexts and various actors, clearly showing the process of negotiation that framed the dialogue between Roman emperors and their various subject groups by the means of unofficial epitheta. B.-M. makes a crucial contribution to a field of research that took one of its starting points in Egon Flaig's ‘system of acceptance’ (E. Flaig, Den Kaiser herausfordern. Die Usurpation im Römischen Reich (1992, 2019²). Whereas Flaig restricted his analysis to groups relevant to the politics of becoming and remaining emperor, studies such as this new volume help to illuminate the wider integration of the Roman empire through the person of the emperor.

The estimable importance of B.-M.'s Dialogangebote might be highlighted by expressing the hope that her study might be followed by comparable works on imperial family members and usurpers in the future.