This book is a study of Cicero's works that deal with philosophy of religion, specifically De Natura Deorum and De Divinatione. These works discuss ideas about the gods put forward by the Epicureans and Stoics, along with Academic criticisms of their views. Cicero was himself a follower of Academic scepticism, although these works are dialogues, so Cicero does not speak in his own voice. It is worth underlining that this study is not primarily concerned with Epicurean and Stoic theology, although inevitably it spends a good deal of time discussing both, but instead with Cicero's project in his dialogues which happen to discuss Hellenistic accounts of the gods. The aim, then, is to present Cicero's works dealing with religious themes as carefully crafted works of philosophy. What was Cicero doing? Wynne's approach places this book within a wider and still fairly recent trend of taking Cicero seriously as a philosopher in his own right rather than merely a source for the views of the Hellenistic schools.

There are a number of ways in which these texts have been read in the past and Wynne gives a thorough account of these in the Introduction. One common approach has been to read these and Cicero's other philosophical works as, in effect, introductions to Greek philosophy for a Latin readership (he calls this ‘the encyclopedia view’, 6). Wynne suggests that instead we ought to see these works as texts aimed at a learned readership already familiar with Greek philosophy, for in various ways they seem to presuppose knowledge of the positions being discussed (9). Another common view, although one now quite dated, has been to see these works as mere transcriptions from a Greek source, and the speed with which Cicero produced many of his philosophical works in a very short period of time has often been taken as evidence for this view. Wynne argues against this, noting that Cicero himself described what he was doing not as transcription or translation but instead as ‘illuminating’ Greek philosophy (11). Cicero does this, Wynne argues, by subjecting the views of the Epicureans and Stoics to dialectical interrogation, and this method also implies that he had a learned readership in mind who would both understand and be able to keep up with this form of argumentation. Wynne also argues that De Natura Deorum and De Divinatione (along with De Fato, although this is put to one side because it only survives in fragments) form a literary unity, all animated by the same issues (46–47, citing Div. 2.3).

What was the issue? Wynne argues that the project spanning Cicero's two works is an ‘inquiry into the nature of the gods in the hope of moderating religion’ (50). By ‘religion’ here he of course means traditional Roman religio, which is taken to be orthopractic, i.e. primarily concerned with correct actions rather than beliefs. So, Cicero's question is whether the theological beliefs of the Epicureans or the Stoics, or indeed the cautious scepticism of the Academics, is compatible with the rites and institutions of traditional Roman religion. According to Wynne, for Cicero this can be answered by examining the question of whether the gods ‘govern the world and care about human life’ (60). For religious practices to be genuinely pious, one cannot simply be going through the motions, so to speak: there must be some coherence with one's beliefs about the gods, and in particular whether they govern the world and care for us. Now of course, the Epicureans famously claimed that the gods did neither of those things, while the Stoics claimed that they did. Thus, one might expect the Stoics to ‘win’ the debate, but their theology implies significant reinterpretation of traditional Roman religion to the point that they too might seem to be impious. Wynne sums it up like this: ‘if a religious agent believes falsely that they do care and intervene then she acts superstitiously, but if she believes falsely that they do not care or intervene then she acts impiously’ (72). This brings us to the heart of Cicero's guiding question concerning the moderation of religion, which is understood as avoiding these two extremes of superstition and impiety. The scepticism of the Academics avoids both of these pitfalls by simply accepting (without affirming or denying) the traditional view of the gods associated with Roman religion.

The central chapters of the book examine the Epicurean, Stoic, and Academic arguments in De Natura Deorum, and then Stoic and Academic arguments in De Divinatione. Wynne is a thorough and careful reader of these works, going through the fine details of the arguments in Cicero's Latin texts. While in places this can sometimes become laborious when Cicero has himself been clear enough, on the whole Wynne's meticulous approach is only to be applauded.

There are inevitably going to be a few minor points over which one might quibble. For instance, the statement that Stoic lekta can only be uttered by the rational (122) would seem to commit the Stoics to the view that children are unable to convey meaning in speech. There are also illuminating moments, such as the parallel between the Stoics’ account of their architect god and Vitruvius’ definition of the ideal architect (131). Other readers will no doubt come up with their own lists of quibbles and illuminations. But anyone interested in Hellenistic theology or Cicero the philosopher will want to read this book. The same should apply to people interested in Roman religion, for Wynne's central argument is that these works by Cicero are primarily about how Romans ought to think about their own religious practices and whether the Hellenistic schools of philosophy can help them out in this task. Appendices set out Stoic religious terminology in Greek and Latin sources, Epicurean arguments against the theological views of previous philosophers, and a Stoic classification of the gods, all adding to the thoroughness of Wynne's study.