D.'s work is devoted to Cicero's dialogue De natura deorum, which, as he explains, for a long time received only somewhat one-sided interest from researchers. The older Quellenforschung in particular largely saw it as a hastily written work, highly dependent on its Greek sources. D.'s study clearly sets itself apart from this tradition, aiming to reveal De natura deorum as a dialogue shaped by Cicero's academic scepticism and to show that many of the text's difficulties can be attributed to an emancipatory objective (pp. 24–8). The emancipatory character consists in the fact that the reading stimulates readers to form a critically undogmatic and culturally sensitive judgement (pp. 26–7). This tendency can be recognised in certain passages that D. interprets as auctorial reading instructions. The study is divided into five steps: an introductory part, which deals with the conditions of production of Cicero's philosophical works (Chapter 2), and four further steps focusing on the proem (3), the dialogic elements (4), the dogmatic speech of Velleius (5) and the refutation strategies in Cotta's speech (6).
The chapter devoted to the conditions of production (Chapter 2) deals in detail with the much-discussed question of Cicero's relationship to his sources. D. points out the basic methodological problems of Quellenforschung, especially the facts that clear attribution of so-called sources largely fails due to the lack of names and that the concept of ‘Quelle’ has not been defined more precisely (pp. 30–5). Investigating the most important statements of Cicero in his letters and other philosophical works, D. argues against the typical paradigms of older research, such as mechanistic and dependent use of sources (pp. 49–67), hasty composition of the work, lacking expertise in the philosophy of religion and a deficient working method (pp. 71–98). With regard to the few prominent Greek sources mentioned by name in the correspondence, D. explains that these rather indicate a selective incorporation of source material, not that Cicero directly transcribed longer passages from them (pp. 99–104).
In Chapter 3 D. examines the proem as a place of direct reader guidance. In doing so, he categorises it as a mixed prooemium, characterised by offering both general apologetic and thematic topoi (pp. 105–9). The rhetorical character of the proem serves to prepare readers emotionally and cognitively for the dialogue (p. 110). By drawing attention to the problems of dogmatic philosophising, to the epistemological difficulty of adequately defining the probabile and to the tension between political practice and Hellenistic philosophy, Cicero recommends a decidedly sceptical and culturally sensitive reading of the following dialogue.
Chapter 4 offers a study of the dialogic elements of De natura deorum. D. devotes himself in particular to the significance of the interlocutor of the young Cicero (pp. 147–62), whom he separates from the author. As he explains, the character provides a paradigm of the ideal recipient, offering readers an opportunity for identification (p. 159). The much-discussed ending of the dialogue is a device creating a conciliatory end to the conversation (p. 161) and is intended to promote a sceptical reading of De natura deorum, since the vote is not to be taken by the author but by his character in the past.
Chapter 5 is extensively devoted to the composition and the structure of dogmatic speech, using the example of Velleius. Contrary to earlier research tendencies, D. wants to show that Velleius’ speech has a coherent overall structure. Its function is to provide an introduction to the philosophy of religion and to encourage readers to examine it for epistemological coherence (p. 176). D. points to the existence of three different argumentative strategies, the use of which he examines in detail in various parts of the speech (pp. 190–238). According to D., Velleius’ presentation of Epicurean theology (pp. 238–62) shows that his uncritical reliance on Epicurus corresponds to the author's critical view of authority in the prooemium. The auctoritas motif, the deliberate brevity (brevitas) and the use of technical terms without introduction or explanation make Velleius appear as an Epicurean who brings the doctrines together, but is unable to explain them in the required detail to an audience not familiar with the subject (pp. 258–9). The characterisation of Velleius should not be seen as completely realistic, but as exaggerated for didactical purposes (p. 264). The doxography of his speech would make readers aware that there is no firm basis for judging right and wrong, as Cicero points out in the proem (p. 266). Through authorial commentary and dialogue, the speech is designed in such a way that readers can learn from it and put the reading instructions into practice. The final part of the chapter presents a comparison with the dogmatic speech of Balbus, highlighting their complementary relationship (pp. 268–86).
Chapter 6 is devoted to the various refutation strategies in Cotta's sceptical speeches, dividing them into three groups: a first strategy, tending to criticise, includes, for example, personal, unobjective or distorting attacks on the dogmatic speeches (pp. 291–328); a second distinguishes itself by dogmatic parts (pp. 328–40); and in a third Cotta points out epistemological weaknesses in the comments of the interlocutors (pp. 340–57). D. does not regard Cotta's refutation techniques, which seem problematic at first glance, as weaknesses of the work, but rather as devices that the author implements for his approach as a philosophical sceptic (p. 340). In terms of the extent to which the speaker Cotta is to be understood as the author's mouthpiece, he points out important differences between the two academics, especially Cicero's strict adherence to the mores maiorum in matters of cult (p. 354). On the other hand, D. explains the gaps in the speech with Cotta's independent argument as a sceptic, thus proving the dogmatic speeches implausible (pp. 356–7).
The work differs from previous studies on De natura deorum insofar as D. does not attempt to identify the author's position in the various speeches of the dialogue figures Velleius, Balbus or Cotta, or to dismiss their weak points as deficiencies in the work of the author. Instead, he offers a solution extremely worthy of discussion by looking at the work as a whole and by placing the individual speeches in a complementary relationship to each other. The observation that the author Cicero does not communicate with his readership through individual speeches alone but rather through the entirety of the dialogue and that he wants to invite readers to an unprejudiced, academically sceptical reading of his work, attests to the Roman philosopher's strong reflective awareness of the possibilities of the genre of literary dialogue. In this regard D.'s approach is in line with the results of recent research, which has increasingly dealt with Cicero as a dialogue author and an academic-sceptical philosopher. Therefore, analysis of the individual elements provides a valuable contribution not only to the understanding of De natura deorum, but also to Cicero as a philosophical author more generally.
This assessment is not dampened by the minor points of criticism that must be mentioned. The first is that discussion of the older Quellenforschung is carried out in excessive detail, considering the fact that its influence on Cicero research has already disappeared. Although D. provides a well-founded systematic overview, this could certainly have been done with greater brevity. It is more regrettable that, while in the main part of his work (Chapter 4) D. provides a profound analysis of the structure and argumentative techniques of Velleius’ speech, there is no similarly detailed evaluation of Balbus’ speech. This could have offered a helpful reference point in the evaluation of Velleius’ argumentative strategy. Overall, the second book is only briefly included in the work and remains clearly under-represented. In this context reference must be made to the study by J.P.F. Wynne (Cicero on the Philosophy of Religion: On the Nature of the Gods and On Divination [2020]). Wynne also sees Cicero's academic scepticism as a key to understanding De natura deorum, but he takes a broader view of the subject by including Balbus’ speech and De divinatione. In conclusion, Wynne and D. have produced two valuable works that will benefit philosophical and philological research.
