Amber Gartrell's monograph connects her interests in Augustus succession strategies and the cult of Castor and Pollux at Rome, the subject of her Oxford doctoral dissertation defended in 2015. Its objectives are first, to analyse the history and development of the cult of the Dioscuri in Rome from its arrival to the Julio-Claudian period, while locating this development within the wider socio-political context; and second, to relate the detailed study of a single cult to wider considerations of the role of religion within Roman society.

The analysis is developed over four chapters. The first focuses on the temples of Castor and Pollux, discussing their different phases and rightly emphasising that Roman temples also had functions in the political and cultural spheres. G.'s discussion of the Forum Temple emphasises its political use, especially with regards to its platform. The discussion on the lesser-known temple by the Circus Flaminius is less assured and ‘does not always provide a reliable summary of, or references to, the relevant evidence and bibliography’ (P. L. Tucci, AJA 126, 2022, 100). The chapter as a whole would have benefited from engagement with D. Padilla Peralta's recent analysis of the overall significance and functions of Roman temples (Divine Institutions, 2020).

The second chapter deals with the epiphanies of the Dioscuri in the tradition, ‘epiphany’ being understood as ‘the physical manifestation of a deity or hero in anthropomorphic form’. Rather than attempting to rationalise these accounts, G. stresses that ancients appear to have believed that epiphanies did occur. I agree with the author that they should not be understood in terms of evocatio, not least because that rite was performed during sieges and not in open battle (where the epiphanies are described as occurring).

The third chapter addresses the responsibilities of the Dioscuri. G. refrains from the use of the term ‘patron god’, preferring to discuss divine roles, responsibilities and protection. Castor and Pollux appear to relate to horses and horsemen, especially to the equites equo publico, who performed the transvectio equitum, which commemorated the victory and the epiphany at the Lake Regillus. Castor and Pollux — the latter never celebrated as boxer (the only relevant exception being the Cista Ficoroni) — also appear to be connected to sailors and ships.

The fourth chapter discusses Castor and Pollux as parallels for imperial heirs, as models for fraternal harmony. Drawing on a wide range of media, including art, numismatics and literature, G. examines how the parallel was promoted, starting from Augustus. She argues that it suggested that the heirs were, like the Dioscuri, ‘devoted siblings who would not plunge Rome into yet another civil war’.

I end the review by focusing on one point of detail that illustrates a wider feature of G's approach to Roman cult, namely her handling of the much-discussed question of whether the first dedication of the Forum temple in 484 b.c.e. was to Castor alone or to both brothers. G. favours the latter interpretation, stating that ‘the fundamental characteristic of the Dioscuri was that they were a pair: their existence as gods hinged upon the mythological tradition that Pollux shared his immortality so as not to be parted from Castor’ (17). She acknowledges that the most recurring title is aedes/templum Castoris, but invokes ‘the human tendency to abbreviate’ (18). That might be the case in oral discourse, but it seems less likely when it comes to written sources. The parallel she offers, the Capitoline temple, is less than convincing. While Jupiter's supremacy could certainly cause the elision of Juno and Minerva, it would be different for the divine twins, whose power is not so unbalanced. Nor would the coexistence of a temple dedicated to Castor and the issue of coins where the twins appear together (e.g. those from 211 b.c.e.: 90 and passim) be surprising, as their purposes, functions and recipients were very different.

In one of the few citations of Claudia Santi's recent Castor a Roma, un dio peregrinus nel Foro (2017) — a monograph with which one would have expected more substantive dialogue — G. takes issue with it regarding the differences between the ‘popular’ version of the battle (Dionysius’, in which two young men appear, both on horseback) and the ‘official’ one (Livy's, without any epiphany of the Dioscuri): ‘She [scil. Santi] furthermore argues that the “demythologised” Roman religion in the archaic era would not have accepted such a divine intervention, a characterisation of ancient religion I find unconvincing’ (77, n. 16). But G.'s unitary concept of ‘ancient religion’ may be misleading. All the myths that she discusses in her ‘Introduction’ are Greek. We cannot ignore the fact that it is the Roman cult we are dealing with here. Roman myths worked quite differently from Greek ones: there are no cosmogonies or divine genealogies and their protagonists are the main characters of Rome's history, whereas gods only seldomly appear to interact with them.

A demonstrative argument that the Forum temple was in fact dedicated to Castor alone can be found in a text that cannot be ‘accused’ of abbreviating anything or of lacking space — the Res Gestae. In the Latin version, Augustus mentions both an ‘aedem Castoris’ (§20) and an aedes Honoris et Virtutis (§11). The comparison with the Greek version of the text is evidential: the first temple becomes τῶν Διοσκόρων, whereas the name of the second is totally omitted, proving that there were no problems in ‘rejoining’ the twins for the Greek-speaking readers (who would have found a temple Κάστορος quite strange) and that a complete omission (Honos and Virtus) could be done for reasons other than lack of space.

This digression is not to devalue the author's work — which is remarkable — but to encourage a higher degree of ‘emic’ interpretation by studying the Roman cult starting from the evidence of the Roman cult itself.