I read Marcus Boon's book The Politics of Vibration, Music as a Cosmopolitical Practice a few weeks before the death of the musician, composer and mathematician Catherine Christer Hennix, whose work and life stand at the centre of the writing, informing its timeline as well as its focus on a mathematically calculable yet spiritual vibrationality of music and the world. This sad synchronicity gives the book a particular urgency and timeliness as her passing reminds me of all the other women composers and mathematicians, artists and scientists who have passed without such careful consideration. It is for this portrait of Hennix, drawn between the intimacy of her biography and the calculability of her mathematical music, that I would recommend the book even for those less interested in music or mathematics. Having said that, the book is not a biography thus declared. However, the centrality of Hennix's compositional and scientific work, as well as her personal influence on Boon – he often leaves the scholarly track to emphasise their personal connection – is apparent and guiding his writing and my reading.

The book is composed of four chapters but I understand it to unfold in three parts. The first chapter provides us with a densely referenced and maybe therefore slightly uncritical history of experimental music with a focus on 1960s and 1970s North America, in particular New York, and the impact of Indian Music – Pandit Pran Nath, Hazrat Inayat Khan, Alia Akbar Khan and Ravi Shankar, among others – on its practices and ideologies. This initial writing also lays down the first reference to a vibrational ontology and tries to situate the notion of a sonic cosmopolitanism somewhere between spirituality and mathematics. These two ideas accompany us throughout the book, finding a focus, from chapter two onwards, in the work of Hennix.

The first chapter starts with La Monte Young and Marian Zazeela sitting in one room of the Dream House, their 1966 first realised environment of sustained drones created by sine wave generators and Zazeela's light installation, in Tribeca, New York. They are playing an annual memorial raga cycle for their musical and spiritual teacher Pandit Pran Nath, who apparently lived in this room between 1977 and 1979. This sets the scene for the meeting between Indian and Western music. Boon provides a dense texture of facts and anecdotes that write a history of cross-cultural influence. The chapter is a great resource on Indian music, its social status and practice as well as its musicological contextualisations, and shines a different light on Western experimental music and art of that time, as less in charge but in awe and searching. This meeting however is not unproblematic. The spiritual, ideological and political practice as well as the social status of either music do not always coincide, and I would have liked to read a more critical take on appropriation, political and economic asymmetries and the patriarchy defining this get-together. Nevertheless, the chapter is a tour de force of musical and cultural connections and geographies, and stands as a solid resource and introduction from which further scholarship can find its edges, disagreements and uncertainties.

Throughout this chapter the notion of the vibrational and the cosmopolitical of music and the world are evoked, two terms I am very fond of, and which chiefly attracted me to the book. But while they seem important and relevant to the works mentioned, Boon never really tells us what they might mean beyond attribution, or what their consequences might be for music or the world. Therefore, despite all the historical facts and information, I am left to make the connections myself: to conjure from this history the sense and meaning of the vibrational, and to contemplate what cosmos it generates and thus what political imaginary it might enable. This is in part the problem of musicology which understands music as a definite category and presents either inner textual readings or historical narratives, but rarely writes from listening into speculative materialisations. It is possible that Boon senses these vibrational spheres so vividly that he has forgotten that we might not, and that he could share their access more generously.

The next two chapters promise an application of these so far rather abstract terms through the focus on Hennix. The idea is to ‘consider the work of Hennix as a cosmopolitical practice – a bold attempt at a novel synthesis of “ways of knowing” through music, sound and vibration, that constitutes a “worlding” in a challenging contemporary way’ (p. 77). This is an exciting promise and one that could open music as well as knowledge beyond disciplinary limits, to a cosmopolitical practice, a practice concerned with the interconnections of a common world. However, the text remains too tied to historical facts and the infrastructure of scholarship to truly try these connections.

The observations on Hennix's work are absorbing and important, providing a deep insight into her approaches and thinking as well as her position between mathematical models and artistic invention. However, the text leaves me to do much of the work of connecting these insights to the key terms proposed: to think and sense and feel the vibrationality, to trust and make the correlations that outline the cosmopolitical. It stays too close to the referenced, which overshadows and disables a discussion on the how and the consequence so vital to grasp the political.

This leads to frustrations, which the author might have felt himself as he states that ‘If speculative philosophy's origin can be found in the limits of the linguistic of the discursive then, sound and music obviously arise as one explores the phenomenal zone of those things that are poorly rendered in and as language’ (p. 87). The limit of language to think through what the descriptions (on the vibrational and the cosmopolitical of sound) might mean, also finds expression in his next statement on ‘the world of sounds, frequencies, vibrations that are there but not necessarily there for us’ (p. 88). Similarly, his writing reaches, describes and brings together facts and works, but does not make their experience accessible for us. This proves frustrating while reading, but also intriguing in hindsight as it performs Julia Kristeva's notion of the chora: what is non-representational, indifferent to language, enigmatic and feminine, which Boon evokes at this point, identifying Hennix’ music a ‘trans-feminist vibrational practice of the unconscious’ (p. 116). Therefore I think it is fine that we do not ever get to really know what this vibrational and the cosmopolitical are. Instead, we can imagine them as possibilities, unsaid and between the lines, maybe accessible only through listening.

An idea which Boon embraces when writing the last chapter on DJ Screw, entering a syrupy slowness, added and abetted by Codeine Linctus, enabling a slower listening to really hear. This is the most ‘listening chapter’ of the book and conveys most clearly the presence of the author. I can feel him literally relax and move into his body. The drones and the vibrations are lived, experienced rather than theorised. In contrast to his writing on Hennix, which even in admiration remains cerebral, here Boon conjures an inhabited world, where he is among friends rather than references. He writes a very masculine cosmos, a male neighbourhood, whose slowness critiques the excesses of an accelerationist politics and economics, but whose description still defines a hegemony. Maybe this is Boon's most honest scholarship. And I wonder what would happen to the rest of the book, its tight references and cerebral descriptions, if we would read this chapter first? If we would slow down, become liquid, fleshly, and enter the drone of a stretched-out time rather than think about it?