Research into Roman religion has undergone extraordinary changes over the past 15 years: since 2012, nearly 320 books and monographs have been published on Roman religion from the archaic to the late antique period, exploring various topics related to Roman religion and using methods from nearly 25 different disciplines. In light of this we can say that, compared to its early period in the sixteenth and seventeenth centuries, when it was primarily researched with the help of the methods of classical philology, epigraphy, art history and history, Roman religion has now become a multi- and interdisciplinary research topic, examined by digital humanities, network research, natural sciences, religious studies, literary studies, cartography and many other disciplines. In this context H.’s book does not necessarily reflect the interdisciplinary nature of contemporary Roman religious studies but rather the classical foundations of the discipline. He analyses a topic that takes readers back to the roots and fundamental questions of Roman religious studies in the most classical sense and according to its methods. His monumental two-volume work is arguably the most comprehensive study of Roman religion in the past decade, far surpassing the typically provincially focused or less well-sourced monographs on individual divine agents (monographs on Bona Dea, Silvanus, Mithras, Isis and Dolichenus have appeared in the past decade).
The magnum opus of H.’s scholarly career, the result of several decades of work, is this two-volume study, raising fundamental questions: how can the iconographic and visual forms of an ancient deity, known from written sources (epigraphic and literary), be identified, and according to what typology should they be classified? What functional, ritual and social roles does an ancient deity fulfil in the capital of an empire and in its provinces? In what ways does a deity metamorphose in literary sources, within the context of late antique polytheism and early Christian (monotheistic) discourse?
From a methodological perspective H.’s volume recalls the classical approaches of ancient art-historical and historical analysis, evoking the positivist era of the great corpora, which – through the ANRW and EPRO series – produced foundational collections of sources and their detailed analyses in the second half of the twentieth century. It was during this period as well that the last empire-wide catalogues concerning the Roman Sun God were produced (G. Halsberghe 1972; LIMC Sol-Helios, P. Matern 2002). At the same time H. emphasises in the theoretical and methodological introduction that, despite the vast and rich history of scholarship on the subject, many erroneous claims about Sol still circulate in both popular consciousness and academic literature. One such misconception is the presumption that the Romans worshipped two Sun Gods, Sol Indiges and the Syrian Sol Invictus. In his studies and in this volume H. has convincingly demonstrated that this is not the case: the Romans worshipped a single Sun God, whose visual representations, diverse epigraphic attestations and iconographic evocations rendered him one of the most complex deities of Roman religion – present across numismatic, epigraphic, sculptural and architectural sources, often in the company of numerous other Roman gods.
This monumental work, comprising approximately 1,500 pages, contains eleven major chapters. The first three chapters deal with the historical development and iconographic representations of the Sun God, the attributes that allow his identification and his associated deities. At the end of the fourth chapter, which addresses distinctive, individual depictions of Sol, the logical structure of the text is somewhat interrupted, as H. introduces the catalogue that occupies roughly one-third of the first volume. Spanning about 600 pages, this catalogue lists several hundred objects, arranged into categories from A to L (A: free-standing sculpture, life-size or larger; B: small free-standing sculptures; C: reliefs of Sol and associated divinities; D: mosaics and opus sectile; E: wall paintings and stucco decorations; F: plates and vessels; G: lamps; H: intaglios; J: jewellery, costume and other adornments; K: minor objects; L: coins, medallions, contorniates, tesserae). This catalogue is complemented by several hundred photographs on plates 23–202, published at the end of the second volume. Together, these likely constitute the most extensive collection of images focused on a Roman deity since the volumes of the Lexicon Iconographicum and the Corpus Signorum series. A noteworthy feature of the impressive amount of images is that the majority derive from open-access public databases or publications, or they appear as newly redrawn figures prepared by H.’s family members. The enormous quantity of objects presented in the catalogue – accompanied by descriptions ranging from one or two lines to full-page discussions – makes it impossible to highlight more than a few in detail. Minor errors traceable to specific objects, while perhaps inevitable in a work of this magnitude, hardly deserve special emphasis. They are better understood as reminders of the sheer scale of H.’s undertaking: these days few scholars would attempt to catalogue several hundred objects spanning a dozen Roman provinces and an immense multilingual secondary literature without the support of an international research team and a multi-year collaborative project. The last comparable effort may well have been undertaken by A. Chalupa, who published in Czech a monograph (2023) assembling the entire Mithraic corpus from the western provinces – albeit without photographic documentation.
Although in the preface H. acknowledges a number of international colleagues, the bibliography reveals that, while the volumes and the catalogue aim to encompass the entire empire, the secondary literature drawn upon is largely in English, German, French and Italian. This focus may also explain why H. considers the Hannover depiction of Sol (cat. nr. B1.24, plate 29.4) and the now-lost Apulum bronze statuette (B1.25) to be different objects. In my view, however, it is inconceivable that a Roman inscription could be identical in both Lyon and Apulum; thus, the supposedly lost Apulum piece is in all likelihood identical with the Hannover bronze. An especially interesting category in the catalogue is C.2c, which deals with depictions of Sol on Mithraic reliefs. Although this subsection presents 124 objects – an impressive number in itself –, it could not, for obvious reasons, aim to collect all the known Mithraic reliefs depicting Sol across the empire. Unlike most other sections of the catalogue, which appear to strive for comprehensiveness, this part provides only a selection of Sol’s Mithraic representations. As a result, certain remarkable examples, such as the beautiful depiction of Sol from the Mithraeum of Hawarte or the striking relief of Sol in the Czartoryski Collection in Kraków (CSIR Pologne III.1, no. 27), do not appear in the catalogue. These are, however, minor issues that in no way diminish the merits of this monumental work. Rather, they underscore the potential value of a digital, open-access and continuously expandable catalogue as a worthy continuation of H.’s pioneering enterprise.
In the theoretical introductory chapters H. dismantles and deconstructs a number of erroneous theses that continue to circulate widely in the scholarship. He demonstrates in detail that Roman conceptions and representations of Sol were not merely the diligent adoption of the Greek Helios, but rather the result of a distinctively interpreted, glocal visual language shaped by regional traditions, including inspirations from Etruscan art. H. deliberately leaves open the definitions of key terms such as ‘Roman’, ‘art’, ‘Roman viewer’ or even ‘religion’, yet throughout several chapters he revisits some of the central dilemmas of contemporary art-historical and iconographic-semiotic theory: what did a Roman see when looking at an image of Sol? The sun as a celestial body? The sun as a mythological figure? Or an active deity endowed with agency and priesthood, with whom dynamic religious communication was possible? The answers to these questions are certainly not provided by iconographic typologies. The role of H.’s catalogue and its categories – like those of the CSIR, LIMC and other modern art-historical catalogues – is to offer contemporary metalanguages and interpretative frameworks that classify objects in material, dimensional and only rarely functional terms. Yet these categories do not resolve the fundamental questions posed in the first three chapters, which require engaging with the complex layers of religious communication and with the intricate relationship between image, deity, human and ritual dialogue. The religious practices associated with the Sun God are analysed in Chapter 5 of the second volume, which collects the epigraphic and archaeological sources of Sol’s Roman priesthood. This analysis highlights the sociological aspects of the cult and the central role of the kalatores within it. H. also devotes separate chapters to the literary manifestations of the sun cult and its transformations in late antiquity.
Even more intriguing are the chapters in which H. reinterprets the famous ‘Sol-Christus’ depiction in the Vatican Mausoleum M and the festival of Natalis Invicti (25 December). Following the lead of contemporary theorists of Roman art such as T. Hölscher and J. Elsner, H. ventures into new, critical methodological waters, though without immersing himself fully; he merely gestures towards concepts such as lived religion and cognitive approaches of religion. Contemporary scholars of Roman visual culture, such as A. Haug or P. Kiernan, are rarely cited. Nevertheless, the chapter devoted to the Vatican mosaic brilliantly illustrates and questions P. Zanker’s optimism regarding whether we, from the perspective of modern society, are truly able to grasp the semantic world of the ancient viewer and believer. H. interprets the Vatican mosaic as neither Christian nor pagan, and certainly not as a synthesis of Sol-Christus. He leaves the final answer open but underscores the profound depth of cosmic theology and philosophy in early Christian sources, in which the movement and power of the sun as a celestial body emerge as central themes. He arrives at a similar conclusion when re-examining the widely circulated scholarly myth that associates Sol Invictus with Christmas (25 December). H. emphasises that the linkage between Sol’s festival on 25 December and Christmas most likely spread through the influence of Julian the Apostate and later historiography, particularly the work of H.C. Usener; our surviving sources, however, do not demonstrate a direct connection between the two events. This chapter anticipates the final one, in which H. provides a detailed analysis of the metahistory of the previous literature, through which the very concept and personality of a ‘second Sun God’, Sol Invictus, was effectively ‘invented’ and disseminated. Here H.’s central thesis comes most clearly into view: the Romans did not simply adopt the Greek cult of Helios, but worshipped an authentic Sun God, the Roman Sol, from the archaic period until the reforms of Aurelian. These reforms did not reflect Eastern influence but were shaped according to a distinctively Roman logic.
H.’s work is paradigmatic in many respects: it offers insight into the intricate, centuries-long history of scholarship on Roman religion and its recurrent errors. It demonstrates that even in a field that has long been studied and treated in multiple monographs there remains room for new perspectives, and that basic research – the continual collection of sources – can never come to an end, since the corpus of material evidence expands with each passing decade. At the same time this monumental two-volume study highlights issues that move beyond traditional art-historical analysis, namely the complex, dual relationship between the Roman viewer and believer – one of the most stimulating topics in contemporary research on Roman religion, whether approached through cognitive religious studies, sensescape studies or the methodologies of lived ancient religion. In H.’s volumes Sol, the Sun God, emerges as a multidimensional construct – religious, literary, art-historical and historiographical. He appears as the life-giving celestial body (then classified as a planet); as the mythical Sun God of narratives, associated with other deities and endowed with local and glocal stories; and as a cultic divinity, the object of worship as Sol Invictus. These three dimensions, however, cannot be understood in isolation, a fact underscored by the vast corpus of material evidence that H. has masterfully assembled and analysed over decades of research. Rarely has any Roman deity received such a detailed and comprehensive treatment. While the size and structure of this work make it demanding and often chaotic to read, each chapter stands as a virtually monographic study in its own right – studies that future generations will hopefully continue to engage with, reinterpret and develop further.
