This book lays the foundation of a completely new way of understanding the relationship between Plato and the philosophers of antiquity who were inspired by his thought.

G. starts his study on the true origins of Platonism by pointing out the persistent influence of Friedrich Schleiermacher's interpretation of the Dialogues, which regards them as the only true expression of Plato's philosophy, thus depriving the so called ‘unwritten doctrines’ of any importance; this exegetical tradition, G. says, has only recently been put into question by the findings of the Tübingen school (K. Gaiser et al.) on the value of the oral tradition for the reconstruction of Plato's thought. G. not only draws inspiration from this interpretative approach, but also pushes it to its limits, for example, by proposing a new way of understanding the role played by Aristotle in the history of Platonism: according to G., Aristotle is not an enemy of Platonism, but a Platonist himself, who made use of Plato's conceptual framework in order to solve the philosophical problems that, in his eyes, Plato had left unresolved. This means that Aristotle shared with Plato a fundamental belief in the same basic philosophical principles which, however, he interpreted and explained in a way that sometimes differed from his master's. This common philosophical ground, which G. calls ‘Ur-Platonism’ (UP), is made up of five fundamental elements: anti-materialism, anti-mechanism, anti-nominalism, anti-relativism and anti-scepticism. Both Plato, who can then be regarded as a Platonist to all intents and purposes, and the other Platonists (Aristotle included) tried to offer diverse solutions to the philosophical problems linked with the constitutive elements of UP; the history of these different interpretations of UP, which G. recapitulates in his book, becomes then the history of the Platonic philosophy, from Socrates and Plato to Plotinus. G. considers the last link in this chain of followers of Plato, that is Plotinus, as the most capable expounder of UP, accepting the opinion of Proclus, who in his Platonic Theology 1.1.16ff. (Saffrey-Westernik) calls Plotinus ‘the greatest exegete of the Platonic revelation’ (ἐξηγητής τῆς Πλατωνικῆς ἐποπτείας).

In the initial chapters (2–3) G. discusses the views of those interpreters who either dismiss the evidence of the ‘unwritten doctrines’ by focusing on the Dialogues only (e.g. Schleiermacher's followers) or argue that the true Socrates must be distinguished from the Socrates of the Dialogues, because the former, differently from Plato, had no interest whatsoever in metaphysical problems (e.g. Vlastos, Penner, Rowe). In order to confute the views of these authors, G. develops intricate counter-arguments, which would be impossible to recapitulate here, and comes to the conclusion that, ‘the more tenable position is that the Socrates of the dialogues is from first to last the creation of Plato, representing Plato's philosophical position’ (p. 53). With regard to the debate between ‘developmentalists’ (who believe that Plato's thought was subject to a process of progressive development) and ‘unitarians’ (who believe in the unitary structure of it), G. takes a middle stance, arguing that, ‘the dichotomy developmentalism/unitarianism is a false one. Plato's Platonism and the Platonism of all his followers was continuously developing on the unchanging foundation that is UP’ (p. 81). The other chapters of the book reconstruct the history of the thinkers that developed their philosophical systems out of their interpretation of UP; first, G. considers the case of the direct disciples of Plato, that is, Aristotle (Chapter 4), Xenocrates and Speusippus (Chapter 5); second, of those thinkers who inherited the Platonic tradition, that is, the Academic Sceptics (Chapter 6), the Middle-Platonists (Chapter 7) and Numenius of Apamea (Chapter 8); finally, the concluding chapters of the book (Chapters 9–11) aim at demonstrating that Plotinus' interpretation of UP was the most effective (p. 308).

In this book G. has tried to challenge the illuminist paradigm that regards the later Platonists (such as Numenius and Plotinus) as unfaithful followers of Plato, by showing, on the one hand, that the fundamental philosophical problems of the inheritors of the Platonic tradition are the same as Plato's and, on the other hand, that these problems are, above all, metaphysical problems, such as the relationship between the intelligible world and the sensible one, the derivation of the intelligible world from the idea of the Good/One, the role played by the Soul in the organisation of the chaotic matter and so on. In trying to achieve this objective, G. has developed a research methodology that could be regarded as more philosophical than philological, because he makes use of the philosophical categories of modern philosophy (such as materialism, mechanism, etc.) in order to demonstrate the correctness of his argument, instead of focusing on the philological analysis of the common philosophical terminology used by Plato and his successors and describing how this developed over the centuries without losing its specific identity. Although G.'s argument is convincing, I cannot avoid warning about the risks of applying a modern conceptual framework to ancient philosophy; G. is aware of this risk (see p. 20) but dismisses it too quickly, saying that these ‘terms need only serve as labels, the contents of which must be specified’ (p. 20). The situation is much more complex than that. In order to use these concepts with certainty, we should be able to define first what ancient materialism, nominalism, mechanism, etc. were, how they differ from their modern variants and why they are more effective than historically grounded concepts in explaining the ancient philosophical thought. In conclusion, the main argument of the book, according to which the history of Platonism must be conceived of as the history of the different interpretations of its basic metaphysical structure, could be defended much more effectively if one made use of a different approach, which tried to conciliate the philosophical analysis of the sources available with the strictest philological and historical rigour.