In this feat of imaginative risk-taking and rigorous scholarship, Simon Bayly enlists the word ‘pathognomy’, an archaic term rather than a neologism, to stage ‘an encounter between two vocations: theatre and philosophy’ (p. 1). The anachronistic frisson generated by dusting off the antique practice of tracking evanescent manifestations of affect, encounter and event indicated by voice and facial expression and placing it in dialogue with philosophers like Badiou, Rancière and Levinas does more than titivate this interrogation into the ethics and aesthetics of performance; it is an unusually sophisticated combination as effective as it is surprising.

Under the umbrella of this unconventional thesis, the book places an assemblage of heterogeneous ideas in conversation with each other. Within this dialogic and relational architecture strands and ideas recur, so that meditations on the notion of performance as an indefinite ‘point of suspension’ immanently poised over the threat of ‘fiasco’ and ‘disaster’ are usefully redeployed in proximity to Alain Badiou's ‘event’, and again later echoed in a discussion on the peculiar properties of reverberation that swung London's Millennium Bridge like a child with a skipping rope. Bayly is capable of great imaginative leaps and fond of unlikely juxtapositions, showcasing formidable erudition in a profusion of tangential associations and recondite allusions that, while learned, seems to border on the compulsive. The sourcing of material extends far beyond the perimeters of theatre and performance and into the realms of biology, neuroscience and astrophysics. When used – as it mainly is – as the evidentiary bedrock to supply critical perspective to consideration of an ‘ethics of experiment’, the result is undeniably industry-standard thinking; when Bayly writes things like ‘in the theory of quantum chromodynamics, contemporary physics also provides a further loose analogy to assist in understanding Spinoza's terms’ (p. 104), the effect of the illustration is to steepen the incline of the intellectual terrain rather than render it more easily traversed.

Nonetheless, the book is not so uncompromising as to resist taking the occasional puckish detour into such subjects as child actors, bodybuilding, campanology and David Duchovny's pout, with Bayly even seeming to channel arch etiquette-satirist J. P. Donleavy when observing that ‘particular actors are renowned in the profession for their salivatory habits of performance, which fellow performers must literally face up to’ (p. 178). Indeed it is here, in the gutsy exploration of corporeality, laughing, sneezing, screaming, that Bayly most capably thrives, where a theoretical cosmology incorporating Derrida, Deleuze, Levinas and Lingis is put to work in rehabilitating a contemporary somatics of performance. What this book offers on the study of the fleeting and transcendent is ultimately highly substantial, as well as provocative and wholly scholarly, though like the brief instances of vanishing expression it meditates on, it can prove just as elusive.