Monica Mattfeld's Becoming Centaur enters a market already crowded with recent publications on early modern horse culture, including Karen Raber's Animal Bodies, Renaissance Culture (2013); Donna Landry's Noble Brutes (2008); Peter Edwards's Horse and Man in Early Modern England (2007); and Raber and Treva Tucker's Culture of the Horse (2005). So one might ask what new ground this book clears to justify its appearance.

Mattfeld answers this question with a dedicated study of eighteenth-century riding manuals in service of the thesis that these manuals employed horsemanship as an instrument of masculine identity construction. Early modern horsemen, Mattfeld argues, strove for a state of perfect physical and mental symbiosis with their mounts, a union for which the figure of the centaur provided a popular mythic emblem. Through an introduction and four core chapters, Mattfeld spins this case out chronologically across the long eighteenth century. In chapter 1 she concentrates on William Cavendish, first Duke of Newcastle, and his writings on the manège, which exemplify for Mattfeld a distinctively Stuart model of “Hobbesian, embodied, transspecies” masculinity whose collective nature mirrored that of Hobbes's leviathan in political discourse (23). This ideal of horsemanship, grounded in early Stuart absolutist theory, gradually gave way to schools of equestrianism that were more egalitarian, less ostentatious, “interested in mechanistic, noncentauric riding for pleasure, industry, and the performance of polite and commercial virtues” (10); these new forms of riding provide the subject of Mattfeld's second chapter. She focuses chapter 3, in turn, on the late eighteenth-century riding school of Philip and his son John Astley, Astley's Amphitheatre, where the manège reappeared under new guise, now associated with the performance traditions of itinerant fairs and similar down-market spectacles. Mattfeld then concludes with a chapter on the contemporary critics of Astley's Amphitheatre and similar riding schools, particularly the equestrian satirist Henry William Bunbury, for whom these sites of training nurtured not masculine vigor but foppish effeminacy.

Mattfeld associates the riding arts with the development of masculinity, which is an easy enough connection to make, horsemanship having been regarded as a martial, aristocratic, and intrinsically manly activity at least since the days of Xenophon. The historical narrative Mattfeld pursues—wherein horses first figure as a feature of warrior masculinity, before metamorphosing more or less simultaneously into both a plaything of the privileged leisure class and an instrument of bourgeois commercial culture—is equally well attested. Indeed, the developing leisured elite and the emergent commercial class at times reinforced each other's prestige. Thus, by the end of the Stuart dynasty, Queen Anne and her favorites had begun cultivating the humor that they were private citizens, addressing each other as Mrs. Morley (the queen), Mr. and Mrs. Freeman (the Duke and Duchess of Marlborough), and Mr. Montgomery (Lord Godolphin); it would be intriguing to trace the influence of such new affectations upon evolving ideals of horsemanship.

Mattfeld's title, Becoming Centaur, underscores the importance she places upon composite horse-human relations—relations in which horse and rider form a collective being, at once human and animal, for whom the figure of the centaur provides a mythic exemplar. But given this emphasis, it is surprising how little time Mattfeld spends actually studying the classical myths about centaurs and centaurism—myths that on the whole present the centaurs (for example, in their battle with the Lapiths and in Nessus's attempted rape of Deianira) as dangerously ungoverned and appetitive beings. Mattfeld does make one brief mention of the wise centaur Chiron, “who bonded with [sic: actually tutored] Achilles” (148), but had she pursued Chiron's story more closely she would have learned that he was sui generis: not begotten like all other centaurs by Ixion upon Nephele but owing his shape instead to his conception upon Philyra by an equiform Cronos. As for the riding manuals Mattfeld studies, by my count they mention the centaur myth twice: once in passing, in Cavendish's New Method … to Dress Horses (1667; Mattfeld 22), and once at greater length, in Richard Berenger's History and Art of Horsemanship (1771; Mattfeld 201). Given this paucity of reference, Mattfeld's emphasis on the myth feels like an arbitrary imposition upon her book's subject matter rather than an organic feature of that subject matter itself.

Additionally, Mattfeld's title raises methodological questions that require some mention here. For one thing, the title phrase Becoming Centaur seems to evoke Gilles Deleuze and Félix Guattari's notion of “becoming animal”—an influential recent effort to theorize relations between species. However, Deleuze and Guattari go unmentioned in Mattfeld's book, which instead draws theoretical inspiration from the work of Donna Haraway. This choice becomes a problem given Mattfeld's professed interest in “spectacles of interspecies communication” (205), Haraway having been criticized for a model of cross-species companionship in which most of the authority and communication run one way, from the dominant human to the subaltern beast companion. This model of interspecies companionship accords with most of the horsemanship theory Mattfeld surveys, but it leaves little space for “horse-human communication” (3) beyond the usual dynamic of human command and animal obedience.

To summarize: at its worst, Becoming Centaur subjects readers to long stretches of dissertationese, such as this one-sentence example drawn from Mattfeld's introduction: “By exploring the often controversial and complicated considerations of political horse-human communication alongside the gendering of both man and horse, this book seeks to develop new understandings of gender performance and identity, while interrogating changing conceptualizations of ‘human’ and ‘animal’ during the long eighteenth century” (3). At its best, Becoming Centaur offers readers a detailed study of the genre of horsemanship manuals as these appeared in England or influenced English riding practice in the period from Restoration to Regency, integrating these manuals into a familiar account of the decline of medieval warrior masculinity and its replacement by ideals of gentlemanly leisure and bourgeois commerce.