This bold first monograph explores early Christian theologies of sight through physiology (how did the ancients think our eyes know the world?) and optics (did they think of mirrors as the spaces where our gaze encounters divinity?). It focuses on four theologians writing between the second and fourth centuries c.e.: Tertullian, Clement of Alexandria, Gregory of Nyssa and Augustine. Cain strives to reconstruct their theories of direct and mediated vision as a window into their understanding of our relationship to the created world.

C. is at her best when reflecting on the frailty of humans and the objects they make — flawed bodies and deceptive mirrors, neither perfectly seeing nor perfectly reflecting, yet both tasked with connecting us to perfection. The many positive qualities of this book, however, do not prevent it from making for a frustrating reading experience. Its piecemeal structure is the main culprit: C. seems to discover her aims as she writes, and her choice to add a second introduction (ch. 4, on mirrors) reinforces the sense of fragmentation. Her sampling of four non-communicating authors is first presented as deliberately wide-ranging (11–12), then claimed to delineate a shift in theological concern from the ‘direct and unmediated vision’ of divinity to its ‘indirect and mediated vision’ (84). This shift is ascribed to Plotinus and his ‘popularization’ (sic) of the metaphor of the mirror of creation (1), a claim that is never proved nor argued for. What we are given instead is a discussion of two pre-Plotinian writers who focus on direct sight and two Neoplatonic theologians, Gregory and Augustine, who elaborate on sight and mirrors. Connections between chapters are not teased out until ch. 7, the final one.

C.'s questions are bold and exciting ones, but her answers suffer from an over-reliance on reductive classifications and arbitrary deductions. Her introduction to ancient theories of vision aspires to cover developments from the worship of Ra in 1500 b.c.e. to the New Testament in 28 pages. (Too) much attention is paid to Greek scientific theories and the exercise of labelling these as either ‘extramissive’ or ‘intromissive’ — i.e. as interpreting vision as either a force emanating from the eyes or a result of the encounter between external particles and our sensory organs. Plato's theory of sight is allocated only half a page and restricted to physics (what about the myth of the cave, to mention only the most obvious point of reference for the sight theories of three of C.'s four authors?). We never learn that Plotinus — the alleged pivot of the book — understands vision (of the One) as the act from which the Intellect comes into being (Enneads, V.2.1). Rather, in the absence of both Plato's and Plotinus’ mystical theories of vision, C. reduces Greek thinking on sight to the scientific study of physiology and develops an essentialising thesis–antithesis–synthesis model: if the Greek study of sight, in this rendering, is all about science, the Hebrew Bible conversely conceptualises vision as capturing ‘one's subjective relationship to the divine’ (17; her biblical survey is extremely brief and relies solely on translations). The New Testament then combines and transcends Greek science and the Hebrew Bible by ‘continu[ing] … the visual ties’ to epistemology from the former and to ‘spiritual identity’ from the latter, yet ‘merg[ing] those threads to visual praxis’ (42). This story of synthesis and culmination is grounded on three brief passages, all from different authors.

The book's claim to be tracing a shift from a ‘rhetoric of literal vision’ to one of ‘metaphorical vision’ (7) is reminiscent of the well-worn argument that (early) Christianity metaphorises all that it touches. Conclusions advance such claims as the idea that ancient mirrors are good in intromission and bad in extramission (104), or that analysis of the four central theologians reveals an ‘unexpected’ pattern in that they all use ‘at least two theories of visual perception to describe the complex role of humanity in relation to the world’ (176). C. explains their combinatory efforts as ‘describ[ing] the complexity of human visual perception’ and thus channelling the intuition that ‘vision is subjective, and … combining separate theories … emphasizes and defines this subjectivity’ (178). Multiple problems arise: (1) Why would anyone choose to combine ‘contradictory’ (179) theories to emphasise the subjectivity of vision? (2) The claim that Tertullian merges Stoic and Epicurean theories of vision depends on a questionable reading of De Anima 17 (47); (3) Gregory and Augustine are taken as ‘combining’ Platonism and Stoicism, yet (what we call) ‘Neoplatonism’ was an eclectic philosophical system already built on the fusion of Stoic and Platonic premises.

It is surprising that peer review neither caught these points nor addressed the book's repetitions (C. mentions her interest in Christian ‘agency, identity, and epistemology’ 37 times across 194 pages) or the overreliance on translated texts (quoted Greek is scarce, mostly in footnotes, and at times careless: compare the accent and breathing on eide on 99 and 100). The book presents itself as inspired by Paul's enigmatic ‘Now we see [God] in a mirror, dimly’ (1 Cor. 13:12), but only on 97 do we learn that ‘dimly’ translates en ainigmati, and C. does not ask ‘how one understands enigma to function’ until 185. More targeted feedback might have helped this fascinating project find a better format. The book is ultimately a missed opportunity to build on profound and timely questions to develop something of lasting impact.