P.’s translation, with commentary, of this important treatise of Plotinus is a welcome addition to the growing list of Plotinus translations and commentaries, published by the Parmenides Press under the general editorship of J. Dillon and A. Smith. Other volumes in the series have set a high standard, and P.’s certainly bears comparison with the best of them.

Ennead 5.1[10] is essential reading for anyone wishing to gain access to Plotinus’ philosophical thought, and the emphasis of this volume is on elucidating what can at times be a complex and challenging text. It will be of interest to those seeking to assess Plotinus’ contribution to the development of Platonism in the seven centuries that separate Plato and Plotinus; Porphyry, Plotinus’ student, biographer and editor, tells us in his Life of Plotinus, Chapter 14, that ‘in Plotinus's works both Stoic and Peripatetic doctrines are interwoven, although they lie under the surface’, and further adds that according to a contemporary of Plotinus, Longinus, ‘He [Plotinus], it seems, gave the principles of Plato and Pythagoras a clearer exposition than anyone before him’ (all translations are the reviewer's own). No less significant is Plotinus’ contribution to later Greek, Medieval and Renaissance philosophy, in particular to Christian theology and the Cambridge Platonists. Although all this presupposes a certain familiarity with the thought of the ancient and early medieval world over a lengthy time span, P. succeeds in judiciously selecting enough material from sources before and after Plotinus to allow his readers to trace the origins of his doctrines and to evaluate their influence on later thinkers. Plotinus himself on occasions (e.g. 4.8[6].1.27) remarks on Plato's lack of clarity on certain topics, and 5.1 sees him grappling with one such difficulty, which stems from an apparent failure on Plato's part to explicate just what he means at Republic 509b7, that the Form of the Good is ‘not Being, but even beyond Being, surpassing it in majesty and power’. 5.1 is part of Plotinus’ response to this difficulty. It is a question that he returns to in several of his treatises, for example in Ennead 6.8[39].

There are few translations with extensive commentaries of Plotinus’ treatises in English. 5.1 is an exception in that there is the OUP translation and commentary by M. Atkinson (revised edition 1985). Unlike P., Atkinson includes the Greek text, and the commentary is barely accessible to anyone without a knowledge of Greek. Atkinson's commentary is some three times longer than P.’s, and the cost of the OUP volume is twice that of this Parmenides Publishing volume. Accordingly, Atkinson's work appeals to the specialist scholar, and contains a wealth of linguistic analysis, while P.’s appeal is much wider. The attractive format of P.’s book scores heavily over that of Atkinson's. It comes in a handy ‘pocket-size’ format, with an eye-catching cover and pleasing typeface.

There was a tendency among Plotinus’ Neoplatonic successors to systematise his philosophy, emphasising the distinctions between the epistemological and the ontological, and seeking to establish different faculties of the soul to correspond with a hierarchy of ontological ‘hypostases’. P. makes it clear in his introduction that the treatise is not primarily ‘an exercise in theoretical metaphysics’; rather ‘the central topic … is in fact the self, and the metaphysical analysis takes place within [a] personal and spiritual context’ (p. 1). This principle is expressed by Plotinus at 4.8[6].6.13ff.: ‘[The One] had to move forward ceaselessly until all things reached the ultimate limits of their potential, driven by a power, limitless in every direction, that sends them out from within itself and cannot leave anything without a share in itself. For there was nothing to prevent anything, whatever it was, from having a share in the nature of the Good to the extent that each thing had the ability to participate’. Here in 5.1, and in many places in the Enneads, Plotinus seeks to establish the unity-in-plurality, which is the essence of his metaphysics; P. nails his colours to the mast by abandoning the traditional translation of the title Porphyry gave to the treatise ‘On the Three Principal Hypostases’ in favour of his own ‘On the Three Primary Levels of Reality’, which moves some way in the direction he wants his readers to take, and is perhaps more in keeping with Plotinus’ aim of ‘exhorting us to discover the higher levels of reality within ourselves’. For ‘in Plotinus metaphysics is spirituality, and spirituality is metaphysics’ (p. 2).

The treatise is divided by Porphyry into 12 chapters: 1–2 deal with Soul (both individual and universal); 3–7 with Intellect (Nous) and its derivation from the One; 8–9 (historically) with Plato, Anaxagoras, Heraclitus, Empedocles, Aristotle and Pythagoras; 10–12 with the unity of the One, Intellect and Soul and our apprehension of them, so bringing the treatise back to the self.

P.’s translation is clear and accurate; he has diligently compared a range of translations into English, French, Spanish and German; he perhaps gives less credit than deserved to S. MacKenna's slightly quirky but vigorous and insightful translation (abridged and revised by J. Dillon [1991]). P.’s commentary achieves a good balance between the main thrust of explicating the philosophical aspects of the text, which he does admirably well, and sufficient reference to the works of Plato and his successors, and some comment on the language and reliability of the Greek text (that of P. Henry and H.-R. Schwyzer, editio minor 1964–82). Perhaps in the commentary on Chapter 5 we could have had a wider discussion of the apophatic nature of the One with some cross-reference to 6.8[39]. Similarly, in his note on 6.31 some comment on the ambiguity of the Greek word dynamis (‘power’, ‘potential’) would have been welcome, and on 7.6–8 some explanation of how ‘line’ = ‘sense’. P. provides a good number of cross-references to other treatises without swamping the reader. There are also some interesting and useful pointers to later thinkers such as Proclus and Augustine. All Greek expressions are transliterated and translated. There is a very useful synopsis of the treatise, a select bibliography (but no mention of H. Blumenthal's important work on Plotinus’ psychology), an index of ancient authors quoted and a good index of names and subjects. In addition to P.’s introduction, there is a useful and succinct introduction to the series, common to all volumes, by J. Dillon and A. Smith.

Although this is a relatively early work according to Porphyry`s chronology (the tenth of a total of 54), it was not written until Plotinus was over the age of 50 and is the product of a mature and profound mind. It offers a concise summary of important features of his philosophy, and perhaps of all of Plotinus’ treatises it offers the most ready access to Plotinus’ thought. P. has succeeded admirably in facilitating this, and his book is to be recommended to the general reader as yet unfamiliar with Plotinus’ philosophy and to more advanced students of Classics, philosophy and theology.