The book is divided into two parts of unequal length: ‘Plato's Rejection of Naturalism’ and ‘The Platonic Project’. In a way, the first two chapters of the first part (‘Introduction’ and ‘Platonism vs. Naturalism’) form a third, distinct and highly significant part of the book, along with ‘Concluding Reflections’. The significance of those three chapters is due to the fact that G. successfully breaks out of the Platonic cave of the contemporary history of (ancient) philosophy. The dazzling light outside the cave may, quite naturally, discourage many readers of this book and lure them back into their intellectual comfort zones, but this is the risk that G., deliberately, as it seems, undertakes in this bold monograph. The first two chapters place him among scholars such as Étienne Gilson, Werner Beierwaltes and Pierre Hadot, if I am allowed to place such diverse and original figures in a single category.

What I find as their common ground may be summarised by quoting the letter written (allegedly) by a certain experienced δαίμων, unfavourably disposed towards humankind: ‘But in the intellectual climate which we have at last succeeded in producing throughout Western Europe, you needn't bother about that. Only the learned read old books and we have now so dealt with the learned that they are of all men the least likely to acquire wisdom by doing so. We have done this by inculcating The Historical Point of View. The Historical Point of View, put briefly, means that when a learned man is presented with any statement in an ancient author, the one question he never asks is whether it is true’ (C.S. Lewis, The Screwtape Letters, letter 27). G. does not submit to this. He does ask the question whether Platonism is true, even if he does not answer it explicitly. In Chapter 1 he begins by finding an unexpected ally in Richard Rorty and his identification of philosophy as such with Platonism. G. agrees with Rorty, claiming that Platonism equals true philosophy; so, if we are to defend what he calls ‘the possibility of philosophy’, we have to determine whether there is a distinct subject matter of philosophy and what that is. The pure naturalistic stance, on the other hand, can be reduced to the claim that the modern philosophia naturalis (with all the powerful arsenal of its principia mathematica) is really all that we can know about reality.

Platonism and Naturalism emerge in G.'s monograph as very large categories or, indeed, the two great camps waging war against each other for ages. But in this war there are moments in which compromises, truces and peculiar alliances even take place. In antiquity, Stoicism and in modernity, Descartes or Kant are examples of those who tried to eat the cake of Naturalism and still have the cake of Platonism. And since those two philosophical positions are mutually exclusive, contradictory and antithetical, G. believes that all the ‘half-hearted’, as he calls them, attempts at reconciliation are incoherent. In fact, he proposes no less than an entirely new way of seeing the whole history of philosophy.

In doing this he draws on his earlier studies, especially Aristotle and Other Platonists (2005) and From Plato to Platonism (2013), which form a ‘trilogy’ together with the present volume (but the reader can also see the presence of G.'s earlier work, such as Plotinus [1994] and Knowing Persons: a Study in Plato [2003]), and here comes the part of the monograph that is a brilliant inquiry into the history of the ancient Platonic tradition. G. reminds the reader of his earlier notion of Ur-Platonism, which is based on the five ‘antis’: anti-materialism, anti-mechanism, anti-nominalism, anti-relativism and anti-scepticism. These five are mutually dependent with the effect that you cannot be a materialist without being a nominalist and a relativist and so on. It is all or nothing. The first fully-fledged form of Platonism we know was developed by Plato in polemic with those five elements, and G. shows that the very strength of Plato's attack on Naturalism relies on the interconnectedness of its principles (Chapter 2). In the first part of the book G. presents the way in which Plato confronts naturalists of his time (Anaxagoras and the sophists) and provides outlines of the distinct subject matter of philosophy. The system behind Plato's dialogues is reconstructed in the following chapters (Chapters 3–6). Further on, G. presents the key contributions by later Platonists: Aristotle's theory of intellect and thinking, Plotinus’ unified hierarchy of being and knowing, and Proclus’ and Damascius’ attempts to safeguard the radical simplicity of the First Principle (Chapters 7–9). The reader receives a view from above on what philosophy studies: the One or the Good, Intellect containing the Forms, the individual intellects as true persons, and the material dimension of reality as an image of the intelligible world.

The significance of this monograph cannot be overestimated. Not only is it a highly original and fresh account of the historical odyssey of Platonism from Plato to Damascius (with Aristotle, like it or not, taken on board and, occasionally, tied to the mast), but it is also an attempt to bring back philosophy, as it was conceived of until quite recently, to the late modern intellectual and spiritual milieu. G. provides an antidote to the tragic fallacy of our times, which is the widely held belief that matters such as the existence of God or immortal intellects are a disputed territory between science and religion or (which is even less true) between reason and faith. This dogmatic conviction, defended with so much zeal nowadays, is, perhaps, more dominant wherever Western culture has been influenced by Protestant Christianity, because the Catholic and Orthodox Churches, at least in principle, if not in actual teaching and practice, attempted to hold on to the ancient view of Christian doctrine as vera et divina philosophia (cf. Augustine, Ep. 2.1).

G. points out that in our times Platonism survives almost only within the religious, mostly Christian, context and tries to claim back the intelligible world as a rightful domain of philosophy. Thus, he questions the current orthodoxy, which pronounces – following in the wake of a certain madman who was once reported to have cried that God had been killed – that metaphysics is dead too. We are told that we are better off to leave the study of reality to specialists like Stephen Hawking or Richard Dawkins, who, far from smashing their lanterns on the ground, seem quite confident that philosophy has simply not much to offer any more. Brilliant as those scientists proved to be in their particular fields, they have displayed surprisingly little understanding of what philosophy has always been and still (possibly) is. G.'s work can be seen from this point of view as belonging to a wider intellectual movement, represented by such philosophers as David Bentley Hart (The Experience of God: Being, Consciousness, Bliss [2013]), Edward Feser (Five Proofs of the Existence of God [2017]) and Thomas Nagel (Mind and Cosmos [2012]), which questions the rationality and consistency of contemporary Naturalism.

Given the limited space of this review, I have not focused on the weak points of this great book. I am sure there are many other readers who will find time and place to criticise G. not only for ‘Thomizing Plotinus’ (as has already been done: D.L. Ross, ‘Thomizing Plotinus. A Critique of Professor Gerson’, Phronesis 41 [1996], 197–204), but perhaps also for ‘Platonising Aristotle’ and ‘Plotinising Plato’. As one particular blind spot, however, I would point out leaving aside the whole dimension of contemplation and spiritual exercises. G.'s view of Platonism is and has always been quite scientific and dry in that he downplays the importance of the direct experience of the intelligible world and its transformative and healing power as well as of the spiritual practices designed through the ages to access and cultivate this experience. But since the monograph is (as I confess to hope in a completely groundless bout of optimism) only an avant-garde of the new phase of philosophy's self-understanding, what remains to be studied is not only the relationship between Platonism and the three Abrahamic religions or the contemporary natural sciences, but also the exquisite richness of Platonism as a practical way of life.