Cogitore takes her title from Cicero, who in one of his characteristic moments of high emotion apostrophizes the nomen dulce libertatis (Verr. 2.5.163). Verres has just breached the rights accorded to a Roman citizen by the Sempronian laws, so Cicero may have a technical, juridical definition of libertas in mind. Yet by addressing the name of liberty and not liberty itself he ties his plea to literary and rhetorical tradition (a pedigree enhanced when Gellius quotes this very passage at NA 10.3.13). The sweetness of libertas adds more literary overtones while drawing particular attention to the emotional power of the concept. In this book, C. argues successfully that far from detracting from the vigour of libertas as a political concept, these literary and affective qualities actually enhance it.

C. is clear that analysing the literary expression of ideas contributes to the study of Roman political culture. The result, however, comes across first and foremost as a literary rather than a historical study. Large chunks of the book adopt a traditionally philological approach, tracing individual occurrences of the word libertas (and, to a lesser degree, its cognates) through various authors and themes. C. is justifiably reluctant to propose specific definitions of libertas, instead describing the various contexts in which it appears and analysing its operation in detail passage by passage. An unfortunate result of the discursive style is a certain degree of repetition, and these sections do not always make for fascinating reading. There is much useful material here, though, for those dipping into the text in search of a particular author or episode. The authors treated cover all periods from 44 b.c.e. to the Antonines, and a wide range of genres. Cicero and Livy receive particular emphasis. C. sees the Ides of March as a watershed in political usages of libertas, and the Philippics and Cicero's letters of 44 b.c.e. are key texts in her argument, while earlier Ciceronian material is not treated. The almost complete absence of the de Officiis therefore comes as a surprise, especially in light of Valentina Arena's work on the subject (‘Invocation to liberty and invective of dominatus at the end of the Roman Republic’, BICS 50 (2007), 49–74).

The book is divided into three main sections, each probing the boundaries of the semantic domain of libertas. The first (17–73) explores abstract concepts linked to libertas either by contrast or comparison, moving more or less chronologically by author. The texts invoke libertas again and again as something which must be fought for or defended against attacks. Indeed, its fragility is one of its defining qualities, and its appearance is often a signal of coming violence. Not only is it under attack from outside, but it contains within itself the threat of licentia. C. argues convincingly for the instability and risks inherent in the literary concept of libertas. Its expression as a literary trope contributes to its emotional charge and efficacy as a call to action.

In the second section (75–166), the organization is by topic, tracing the operation of libertas in literary accounts of historical episodes. C. outlines the development of a multi-faceted libertas which could be invoked on the one hand in discussions of the early Republic or in the immediate aftermath of the Ides of March in a simple opposition with tyranny, but on the other hand functioned in Late Republican political discourse and in Augustus' writings as a more complex political idea which combined successful government with the rights of the individual. This was not an empty concept, but an adaptable one. As she moves chronologically through imperial reigns, C. makes good use of coinage to contrast the rise and fall of libertas in official imagery with its appearance in literature. For the imperial period, she sketches out a transformation in which political libertas is co-opted for dynastic use by the emperors, while writers gradually bring together elements of freedom of speech and philosophical, inner freedom into a new libertas which gradually loses much of its connection with instability, violence and opposition.

In the third section (167–219), C. moves to consider important places, individuals, and other symbols tied to libertas in Rome's collective memory. Here the reasoning behind C.'s selection of particular topics is more opaque; individual instances of the word libertas are no longer the key, and some subsections are more closely tied to the wider argument than others. The section on places tied to libertas (171–9) is slight, but the discussion of Brutus and Cassius as liberatores (191–4) makes a useful contribution, highlighting the emotional force of the word as used by Cicero.

Throughout, C. focuses on usages of libertas connected to internal politics, excluding passages she judges to refer solely to the legal status of slave or free or the relationship between foreign peoples and Rome. One wonders how clean such distinctions between the term's different applications can ever be, especially given how successfully the book makes an argument for overlaps and shifts in emphasis over time between concepts of political freedom and freedom of speech. By concentrating on highly charged, explicitly political moments, however, C. is able to move away from legalistic definitions and foreground the emotional and rhetorical appeal of libertas. The fact that libertas was a literary trope is not evidence that it was an empty slogan, and close analysis of its literary operation can bring us closer to understanding its political importance. Though it will not close the debate, such a re-framing of the question is welcome, and C.'s emphasis on the affective aspects of libertas is particularly worthwhile.