This volume is dedicated to tracing the development of the idea that the wise should rule, presented most forcefully and famously by Plato in the Republic. The title is somewhat misleading, since it is not really a study of how Plato's own model of the philosopher-king was realised in antiquity. Whenever Plato's model is compared with the reality – be it by Plutarch (as discussed in Chapter 3, ‘From Plato to Plutarch’) or by D. himself – the conclusions are disappointingly familiar and expected: people fell short in one way or another. Indeed, the choice to emphasise time and again the Platonic paradigm of the philosopher-king risks generating misleading impressions about the primacy of Platonic thought on good kingship in antiquity. More significant are the striking proliferation of kingship treatises and philosophic advisors of all persuasions throughout the Hellenistic and Roman periods and certain kings' and emperors' real engagement with philosophical tenets and kingship theory. The majority of the book's interest concerns these topics.

The introductory chapter lays out the key aspects of ‘the king’, looking in particular at evidence from Homer and various historical sources. D. identifies three fundamental spheres of interest: the military, the legislative and the religious. The remaining chapters trace how philosophical thought on kingship developed over time with respect to these three fundamental aspects, beginning with Plato. The chapter on Plato summarises clearly and briskly his thinking on kingship in a number of dialogues, most notably the Republic, Statesman, Timaeus, Critias and Laws. A considerable amount of detail is omitted, but the chapter effectively establishes the Platonic paradigm that is referred to throughout the book.

The next chapter, ‘From Plato to Plutarch’, looks at the Hellenistic period. D. makes the point that philosophical concerns are by no means clear when it comes to the actions of Alexander the Great and his successors, even if the tradition surrounding Alexander in particular gives some kind of theoretical justification or framework for his brilliance, virtue and so forth. He then notes the interesting developments once the Cynics and Stoics arrive on the philosophical scene, in particular their insistence on the radical thesis that the virtuous soul is both necessary and sufficient for being king. This position is clearly tempered by the proliferation of kingship treatises and the efforts to advise and guide those actually in the political office of king. The treatment of this period is illuminating and there is a great deal of detail provided with examples of kings and philosophers interacting in various ways. The chapter ends with a discussion of Plutarch's thinking on kingship, with particular reference to his Lives. The results of this section are somewhat unsatisfying. D. makes much of the ways in which Plutarch can be read as comparing various historical figures with Plato's ideal, but whether this is Plutarch's real interest is dubious, and D. is sometimes forced into making vague insinuations (deserving of more discussion) and into admitting that Plutarch even regards the philosopher-king as a potentially dangerous ideal.

From Plutarch we move to Marcus Aurelius. D. outlines his education and the various challenges that he faced as emperor, before exploring the extent to which Stoicism informed his reign. The core Stoic tenets in the Meditations are stated briefly, and a number of parallels between his actions and those tenets are noted. D. concludes that Marcus Aurelius was not a perfect Stoic king or emperor in the strict sense; rather he sought to mediate between Stoic ideals and practical necessities. This is a rational conclusion, but supposedly it is sufficient to qualify him as a philosopher-king. This seems a step too far: there is little remarkable if a philosopher-king is simply a king who (to some degree) determines his actions by agonising about philosophical theory and how he might best put it into practice given the realities on the ground.

The next chapter focuses on Julian the Apostate. D. sets out to analyse Julian's career in terms of his philosophical commitments to essentially Neoplatonic tenets. Julian's philosophical writings are examined, in particular those containing material on kingship. D. argues that as emperor Julian took care to rule in accordance with these writings, citing a number of parallels between his written thought and actions, and so Julian too supposedly warrants the title philosopher-king. Again, one might worry that the title denotes little more than a ruler who does some philosophy, thinks seriously about matters such as good kingship and whose actions are to some extent informed or influenced by specific philosophical tenets.

The final chapter, ‘From Moses to Modernity’, seeks to establish continuity between the ancient and modern contexts. D. outlines how Judaeo-Christian ideas begin to fuse with those of the Greek tradition, dwelling in particular on the Jewish Neoplatonist philosopher Philo, who identifies Moses with Plato's philosopher-king. D. then provides a number of examples that show how this kingship tradition, with its ancient roots, is maintained throughout the medieval and early modern periods and continues to develop into the nineteenth and twentieth centuries and the present day.

This volume is an ambitious study that tackles a huge range of rich and complicated material. To fit it all into a book of this moderate size is a hard task. D. manages to do so, but it involves some major sacrifices. The style is rather light and breezy, with descriptive summation when the complexity of the material often deserves a deeper treatment. Full critical engagement with debates in the scholarly literature is frequently lacking, even when it is urgently warranted. For instance, in the second chapter, discussion of the intriguing seventh Platonic letter simply passes over important disputes about its content and authenticity, and there is no real treatment of the ways in which it engages with other texts in the Platonic corpus, most pertinently the Republic and the Laws. There is more acknowledgement of critical issues in the endnotes, but little explicitly in the main text, and this should be remedied. One of the major results of this is that specialists on any of the major texts or figures would turn towards other works rather than engage in depth with this book. Despite these reservations, the book succeeds in highlighting the force of the idea ‘let the wise rule’ and the ongoing human preoccupation with the relationship between wisdom and political power. With its broad scope, brisk and accessible presentation of the fundamental issues and useful bibliography, it would serve well as an entry-point for those interested in gaining a handle on ancient philosophical thought about kings and the institution of kingship.