By Daniel Heller-Roazen. (Parallax). Baltimore, MD, Johns Hopkins University Press, 2003. 206 pp. Hb £33.50. This intelligent though at times irritating book follows the working through in the Romance of the Rose of a strictly medieval trajectory given, Heller-Roazen argues, to the concept of contingency by Boethius. Boethius, it is claimed, coalesced two terms that were quite distinct in Aristotle, that of ‘potentiality’ and that of ‘happening’, thereby radicalizing Aristotle's conception of contingency so that ‘it designates not an abstraction or a merely hypothetical possibility but something that exists and which, as such, takes place’ (p. 19). Under the impetus of Abelard, this Boethian reworking developed a more paradoxical cast. Oscillating between realization and non-realization, ‘possible things are those things that exist when they do not exist and do not exist when they exist, and that are thus naturally capable of turning over into either of the two by virtue of the ease of their nature’ (pp. 22–23). For the medieval period, then, contingency involves the doubling of a thing with its negation and the positing of a virtual place in which things could happen otherwise. Although Heller-Roazen lays claim to the unadulterated historicality of his study, such formulations attest the influence of post-structuralist philosophers especially Agamben, some of whose works Heller-Roazen has translated and who provides a fulsome endorsement on the back cover. In three subsequent chapters addressing respectively subjectivity, the figure of Fortune, and the theme of knowledge, this idea of contingency is shown to inform the poetic practice of the whole of the Rose, a text both preoccupied and pervaded by doubling, negativity and virtuality. By far the best chapters are the first, which lays the philosophical foundations of the project, and the last, which is also philosophical in cast and centres on Nature's discourse on foreknowledge and free will. The weakest is the chapter on subjectivity which adds very little to previous scholarship, notably that of David Hult. Thus, while the book claims to be as much about poetic practice as about the history of ideas, I think it is much more successful on the latter front than on the former. Despite occasional lurches into self-importance and a lack of generosity towards other critics, this is a clever and generally cogent book on a fascinating topic.