The book includes an introduction, providing a general account of the structure of Met. Delta and of its role within Aristotle's Metaphysics, a new French translation, a running commentary and an essay on the main conceptual tools employed in Delta. The translation is accurate and clear and, while there are a few controversial choices, they are all discussed in the notes to the text or in the commentary. The commentary mainly provides a brief reconstruction of the various sections in each chapter and references to parallel passages, whose full translation is usually given. The most interesting issues are raised in the introduction and in the concluding essay.

In the introduction, B. and S. suggest that the role of Delta within the Metaphysics is that of providing the general account of the attributes of being qua being as anticipated in Arist. Met. B 1, 995b21–25 and Γ 2, 1003b32–1005a18. This account of the role of Delta is in contrast to the approach of most modern commentators, who tend to regard the book as a relatively independent philosophical lexicon, but it can count on a solid Peripatetic tradition. In fact, Alexander of Aphrodisias, in his commentary on the Metaphysics (Alex. In met., Hayduck 344.2–345.20), relies on the conceptual vicinity between Delta and the investigation on per se attributes of being qua being in B and Γ to argue in support of Delta's authenticity and appropriate location within the Metaphysics. In proposing their view, B. and S. are well aware of the fact that some hints within and without the Metaphysics suggest that Delta might have originated as an independent writing. However, they argue (pp. 18–20) that, even if this were the case, its insertion within the Metaphysics can be fully justified on the basis of its systematic relevance with respect to the project outlined in Met. Β and Γ.

Although this overall approach is both interesting in itself and backed up by an authoritative ancient and medieval tradition, one question should be asked in order better to assess Delta's credentials for being the place where Aristotle discusses the attributes of being qua being. Two aspects in the outline of the enquiry into the attributes of being in Γ 2 must be taken into account. On the one hand, Aristotle suggests (Met. Γ 2, 1004a931) that the analysis of notions such as unity, plurality, identity, otherness, difference, contrariety, etc. should follow a relatively systematic pattern. On the other hand, the list of attributes of being he gives (ibid. 1005a13–18) is not complete, and it is not clear whether and how systematically such a list could be completed. If we focus on the second aspect and on the coverage of the notions mentioned in Γ, Delta is certainly an appealing candidate for being the place where that enquiry is carried out. If, on the other hand, we focus on the first aspect, there is one other book in the Metaphysics which certainly displays a striking vicinity with the outline in Γ 2, i.e. book Iota. I cannot discuss here the complicated issues emerging from a detailed comparison between Delta and Iota (for a more detailed account of some of the issues involved see L.M. Castelli, ‘Greek, Arab and Latin Commentators on per se Accidents of Being qua Being and the Place of Aristotle, Met. Iota’, DSTradF 22 [2011], 153–208), but the extent to which the enquiry into the attributes of being qua being is supposed to be a structured and systematic one deserves, in general, closer scrutiny. Interestingly B. and S. approach the issue of the structure and role of Delta and partially similar writings in spelling out similarities and differences between the structure and goals of Delta and the Categories (pp. 19–20).

By stressing Delta's relevance with respect to the general plan of the science of being qua being, B. and S. also question the idea that the common trait of all notions discussed in Delta is their being pollachôs legomena, ‘things that are said in several ways’ (pp. 17–18, 213–16). In particular, they isolate three chapters (Chapters 3, 13, 27) devoted to univocal notions and sketch three main patterns under which most chapters of Delta are supposed to fall: (a) cases in which an explicit relation between the different accounts of the term at stake is given; (b) cases in which no explicit indication as to a unification of the different accounts is given, but a unification can be reconstructed on the basis of explicit indication; (c) cases in which it does not seem possible to establish any clear relation between the different accounts of the term at stake. Furthermore, the role of four main dichotomies is discussed (per se / per accidens; in potentiality / in actuality; primarily / derivatively; in the proper sense / metaphorically). Several points would deserve a fuller discussion than can be provided here (for example, the idea that the dichotomies play different roles in different chapters and that in some cases they only introduce auxiliary distinctions seems promising), but I shall confine myself to two remarks on the overarching issue of the patterns displayed throughout Delta.

First, one might wonder what the basis for distinguishing between patterns (b) and (c) exactly is. In order to show why the distinction is problematic, I shall confine myself to one particularly controversial example. B. and S. claim that chapter 2, on the different ways in which aition, ‘cause’, is said, displays the second pattern: Aristotle nowhere explicitly says what the common notion unifying the different accounts is, but we have enough elements to reconstruct the unification. The common notion would be that of being responsible or accountable for something (‘responsible’ is the first meaning of the adjective aitios) and Aristotle says that aitia are, with respect to their eidos (tôi eidei: 1013b29), of the given sort and number. B. and S. translate the expression tôi eidei with ‘spécifiquement’ (p. 29) and consistently maintain in the commentary (p. 88) and in the concluding essay (pp. 219, 221) that the basic difference between the four cases is a difference between species of one and the same genus. While eidos certainly can be used in this technical sense to indicate the species of a genus, it is often used in a more generic and nuanced way and it is far from clear that it retains its technical meaning in this context. However, B. and S. seem to take this as a sort of platitude and do not comment on the fact that the unification of the four kinds of causes is a very controversial issue in the literature on the topic.

Second, with respect to the possibilities of unification of the various accounts, B. and S. speak of the relation between the common notion and the different uses or accounts of the terms given in each chapter in terms of addition (p. 215). It seems that two rather different cases fall under this rubric: in some cases the common notion is a generic one which is qualified in the other accounts (e.g. in Chapter 3); in other cases, it is a notion which is implied by or referred to in the other accounts (e.g. in Chapters 4 and 12). B. and S. seem to treat these two relations as equally viable for the purpose of the unification of the different accounts falling under pattern (a) and (b), but it would be interesting to see whether anything more can be said on the structural similarities and differences between these two strategies within and without Delta.

These are only a few of the deep issues that make this book a thought-provoking reading and will stimulate further discussion on Delta. At the same time, its accessible character will make it a useful tool both for those who approach the text for the first time and for more experienced readers.