B.'s volume is a monumental work: in its length (approaching 500 pages); in the astounding range of topics it tackles, from metaphysics – indeed from the basics of Stoic ontology to theories of causation, composition and constitution – to epistemology, to philosophy of language, to ethics; and in the wide variety of sources it calls upon, spanning centuries, schools of thought and genres.

At its core the book is a compelling rehabilitation of lekta. Far from being an afterthought in the Stoic materialist ontology or from being limited to the linguistic or logical realm, incorporeal lekta are, in B.'s view, ‘a keystone’ of the entire Stoic philosophical system (p. 80). Moreover, the ontological status of lekta, one of four ‘incorporeal’ types of entities in Stoic physics, which are said to have ‘subsistence’, is not, B. argues, an inferior one, falling short of existence (the status of bodies). Contrary to what has commonly been thought in the literature, lekta are thus, on this account, ontologically independent and a crucial feature of the Stoic system.

The case is made by considering the status and role of lekta in seemingly all areas of Stoic theory. Chapter 1 begins by establishing the unity of the Stoic system, one that is deeper than sometimes recognised. The well-known tripartition of ethics, physics and logic is not, according to B., one that runs deep. Instead, she convincingly shows that the parts are interrelated and truly unified, a view that is now often taken for granted in the scholarship, but had yet to be the subject of such thorough exposition. Chapter 2 underscores the interdependence of the Stoic notions of signified (sēmainomena), lekta and impressions. In so doing, it considers the relationship of lekta to language and the mind, and in particular rejects the view that lekta are dependent on either. Chapter 3 delves further into Stoic ontology to establish the distinction between bodies and incorporeals. The latter, B. argues, are central to Stoic ontology – and not, as some have thought, problematic – not least because their incorporeality makes them fit to be objects of knowledge and teaching. Chapter 4 continues the account of the psychology of teaching and proceeds to develop the core view of the book, according to which lekta are constitutive of reality, there to be said and grasped by the mind.

Bringing the ontology in conversation with semantics, Chapter 5 argues that lekta are separate from and, importantly, not dependent on language. Lekta are there to be said and can ‘get said’, but are not dependent on being or getting said. The point that there is no ontological dependence of lekta on language is convincing and well taken, though the further argument that this should rule out the translation of lekta as ‘sayable’ is perhaps weaker: something can be sayable though it never gets said. Indeed, B. admits that ‘lekta thus have an articulation which makes them capable of being expressed’ (p. 201). It may help B.'s argument here to define and distinguish more clearly between what is said, what is expressed and what is uttered. Chapter 6 considers the sense in which lekta get said and are there to be said, rejecting the idea that complete lekta are speech acts (in the Austinian sense) and re-affirming the thesis that lekta ‘co-constitute reality by holding together its logical structure’ (p. 229). Chapter 7 places lekta in the context of the Stoic theory of causation, in which a body is said to be a cause of a lekton (a katēgorēma, or predicate), and goes on to draw links to ethical debates about responsibility. Chapters 8 and 9 consider the semantics and grammar of lekta in greater depth, detailing the different kinds of lekta and establishing the fundamentality of the proposition (axiōma).

Each chapter makes novel, often bold, contributions. The discussion throughout is impressive in its capacity to consider each piece of evidence and each view in its context. Evolutions within the Stoic school are traced where possible. The Stoic views are frequently linked to or contrasted with that of others, from Plato and Aristotle, to the Epicureans, to the commentary and grammatical traditions of late antiquity. Though more recent work is less systematically discussed, B.'s coverage of earlier secondary literature is similarly broad. Specialists will find much to be challenged by and, no doubt, to disagree with. A review of this length cannot possibly do justice to the richness of the book and the many interesting and exciting avenues for debate it opens. Let me raise just two general questions.

The first regards the ontological status of lekta. B.'s thesis is that lekta, which are incorporeal and subsist, are ‘real’ and ‘constitutive of reality’. Yet she does not quite tell us what their reality and subsistence amount to. B. seems to conceive of what is real as what is extra-mental. How or whether this maps on to Stoic ontological commitments is not clear. This is all the more troublesome given that, by B.'s own admission, the Stoics consider all reality to be created by and thus dependent on the mind of God. It is similarly difficult to discern just how subsistence differs from existence, only that, on B.'s view, it is not inferior to it. A more explicit articulation of what this ontological status consists in would be particularly welcome since B.'s account rests in large part on a proliferation of entities whose status is equally left for the reader to puzzle out. To take just one example, B. distinguishes an object (say, Socrates) from this object qua ‘case-bearer’, the so-called tunchanon, ‘with respect of which a katēgorēma [i.e. predicate] subsists’ (p. 407). The lekton ‘Socrates walks’ does not predicate walking of Socrates himself but of another intriguing entity, a ‘case-ptōsis’, born by the tunchanon (p. 354). The nature and status of both the case-ptōsis and the tunchanon, and indeed why the latter need be posited as an independent entity at all, could be further expounded.

This leads to my second question, which regards the relationship of these various entities to each other. Using the above example, how a tunchanon relates to either the object or lekton it corresponds to or the case-ptōsis it bears is somewhat mysterious. More broadly, questions remain about how lekta relate to ‘states of affairs’: they are sometimes said to ‘correspond’ to them (e.g. p. 360), elsewhere they seem to be identical with them (e.g. p. 407). Similarly, the relation of states of affairs to objects in the world is left underspecified. These are just two examples. Given the number of moving parts in the intricate and sophisticated picture B. paints, both in the context of causation and in that of semantics, a clearer articulation of how the parts fit together – and, at times, why they need be distinguished – would be welcome.

As might be evident even from these brief observations, this is not a book for the uninitiated. Though some efforts have been made, for example relegating Greek and Latin quotations to footnotes and including only translations in the body of the text, those without knowledge of Greek and Latin will inevitably face hurdles, not least the choice to transliterate a large number of key terms, and the many forays and excursions into detailed points of grammar by means of which important exegetical points are carefully defended. More generally, the Stoics’ many idiosyncrasies, by and large left intact and indeed fully embraced by B., will puzzle those less familiar with their system of thought. Specialists, on the other hand, will appreciate B.'s eye for detail and her deftness at extracting evidence from disparate sources with an admirable combination of ingenuity, caution and sensitivity to context. In short, this is a work not for the curious dabbler, but for the keen and adventurous reader who will be rewarded for daring to take the plunge.