In his Life of Charlemagne, Einhard famously claimed that the Frankish ruler enjoyed listening to the works of St Augustine at meal-times, and in particular (praecipue) Augustine's City of God. That comment has often surprised and intrigued Einhard's readers, yet there has been surprisingly little research on the influence of Augustinian political ideas on Carolingian Francia, despite all the recent work on the Carolingian state (recently revisited in Jürgen Strothmann's new book, Karolingische Staatlichkeit).
In this book, Sophia Moesch contributes to remedying this. She studies the reception of Augustine's political thinking, as expressed in his City of God, in the work of two writers in Carolingian Francia, Alcuin of York and Hincmar of Reims. These authors are chosen to represent early and late Carolingian readings of Augustine, and for their proximity to rulers: Charlemagne in the case of Alcuin, and Charles the Bald in the case of Hincmar.
After a methodological introduction which positions the work in relation to Auerbach and Skinner, Moesch divides her book into three parts, on Augustine, Alcuin and Hincmar. The part on Augustine assesses his ideas about worldly rule, and unpacks some Augustinian words and concepts. It emphasises some of the inconsistencies, or enduring tensions, in his work. The two parts on the Carolingian authors share the same organisation: a chapter on direct quotations, especially in these two writers' letters, and a chapter on indirect engagement with Augustine's ideas. A short conclusion wraps things up.
On the basis of this structure, Moesch offers some important insights. Augustine's political ideas are sometimes thought to have been too complex for the early medieval context--this was the thrust of Arquillière's 1933 work on L'Augustinisme politique--but Moesch's book suggests this is an oversimplification. Alcuin's use of Augustinian terminology to describe Charlemagne's rule may seem to run counter to Augustine's own ideas about worldly rule, but it is not that Alcuin did not understand Augustine. Rather, he was consciously arguing that even though Augustine thought no worldly rule could be truly just, Charlemagne showed that a realisation of the City of God on earth really was possible. Alcuin draws on Augustine "to make a positive statement about Charlemagne and the Carolingian 'state'" (70). In other words, he "manifestly reinvented Augustine to suit his own project" (113).
The densely argued section on Hincmar draws especially on the so-called Expositiones ad Carolum regem, "probably Hincmar's most interesting piece of writing" (168--though readers may have their own favourites!) and his De regis persona, both accompanied with generous English translations. Moesch suggests that if Hincmar's attitude to the interplay between religion and the secular seemed at odds with Augustine, that again is not so much a misunderstanding of the North African bishop's work, but a reflection of the changed context. For Hincmar, the "church" was far more institutionalised a concept than it had been for Augustine, and the "state" far less; and Hincmar was moreover more interested in the ruler than in the society as a whole that he ruled. What we are dealing with is therefore not so much a misunderstanding of, then, as a creative engagement with Augustinian ideas, though this took very distinct forms for these two writers.
The book is based on a 2014 PhD thesis. There are some bibliographical updates up to 2017, but no further. That is not in itself a problem, for we all have to stop reading at some point; but it is a pity that Moesch was not able to use the 2018 MGH volume of Hincmar of Reims's letters.  This might have helped clarify a few points where her readings of Hincmar's letters are not assured. For instance, she has Hincmar say that Charlemagne was "robbed of his religion" (172) by flatterers at his court. But as the new MGH edition makes clear, in reality Hincmar simply says Charlemagne was deceived by these flatterers (an impersonal subreptum fuerit). Annoyingly the book has chapter endnotes rather than footnotes, which makes following up the Latin and references in general harder.
A study such as this, based on two authors, and sampling only some of their work, cannot of course claim to be definitive. Indeed one of this stimulating book's merits is to demonstrate the potential value of, and the need for, a more systematic study of the influence and appropriation of Augustinian ideas in Carolingian Francia, to shed light on the many debates of this fecund period. It might finally be noted that this book is available for free, open access, as a pdf file (as too is the original King's College London PhD thesis on which it is closely based).  That is an especial boon in these pandemic times for which many readers will be grateful. If publishers such as Routledge are going to insist on endnotes, however, perhaps they could make them into hyperlinks for online publications?
1. Reviewed by this reviewer for TMR: https://scholarworks.iu.edu/journals/index.php/tmr/article/view/27139