This book's title raises expectations of a meaty analysis of Bernard of Clairvaux's theoretical reflections on the relationship between the spiritual and secular powers, possibly set against the turbulent background of his own lifetime with its tensions and conflicts between the two. In fact, Alice Chapman offers something rather different. In what sometimes appears an insufficiently reconfigured postgraduate dissertation, her volume is primarily a semantic analysis of Bernard's use of the two terms auctoritas and potestas: the former a quality ascribed to the Church; the latter an attribute of secular rulers but with wider application through the Church's power over sin. The focus is precise: on the 152 occurrences of auctoritas in Bernard's works, and the 331 uses of potestas. There is an obvious association with the Gelasian doctrine of the two powers, which provides the cue for a lengthy discussion of the pre-Bernardine history of references to the Gelasian text in chapter i; but, as Bernard never actually cites the doctrine, this merely postpones the main argument. Three chapters deal explicitly with auctoritas: in terms of ‘Ecclesiastical order’ (chapter ii), ‘Monastic order’ (chapter iii), and in chapter iv looking at ‘Connection and application’. Their concern is with spiritual structures and authority; discussion of the secular side, together with the spiritual, appears only in chapter v: ‘The cooperation of sacred authority and temporal power’. A brief conclusion draws things to a close. The discussion is detailed, but at times worrying and confusing – confusion arising in part because the two Latin terms appear imprecisely differentiated, and are frequently discussed by using the English ‘authority’ and ‘power’ in ways which tend to merge the Latin through the ambiguity or similarity of the English words. The tunnel vision of the linguistic analysis is at times exasperating: one almost shrieks out in frustration when told where plenitudo potestatis appears in the texts (p. 125), with no meaningful attempt to excavate its meaning as a term. That failure to look outside the texts to the contexts, to turn from the written to the writer, is the book's most worrisome feature. Chapman insists that Bernard contrasts monasticism and knighthood (pp. 75–6), saying nothing of his support for the new knighthood of the Templars until p. 187. Bernard's self-proclamation as the most overt challenge to the core themes of Chapman's (and his own) arguments is similarly ignored until it can no longer be, and then receives only scant attention (p. 158). Bernard was a man of actions and words; authority and power discussed without examination of how they were exerted become empty constructs. This book certainly constructs, but its failure to engage effectively with Bernard as well as his works leaves a void at its heart.