In this short book developed from his plenary lecture at the International Congress on Medieval Studies in 2016, Ian Wood returns to the foundational work of Edward Gibbon and calls on historians of the fourth through seventh centuries to reconcile the multiple approaches typically applied to studies of this transformative period (ix–x). Wood argues scholars have emphasized either religion and culture or social, economic and political factors, leaving us with essentially two “parallel worlds” (31–34). While Wood acknowledges that Gibbon's explanations for the decline and fall of Rome are no longer adequate, he contends that modern scholarship would benefit from following the eighteenth-century author's integrated focus on social, economic, political and religious dynamics (2–3, 31, 34).

Wood begins by breaking down the main points of Gibbon's famous thesis and presenting major scholarly responses to them. Wood notes how political and social developments—such as wars, the Industrial Revolution and modern refugee crises—have contributed to theories about the role “Barbarians,” social-class struggles, tyrannical rulers, and the economy played in the collapse of the Roman West and the successor kingdoms (3–9, 21–22, 24-26). The survey includes nationalist and Marxist interpretations, and the heated debates on the ethnic composition and scale of the Germanic migrations or invasions (21–22). Wood also examines scholarship on the role of religion, starting with nineteenth-century reactions to Gibbon's negative view of Christianity, which tended to credit the Latin Church with salvaging classical civilization or filling a void after the “corrupt empire” was overthrown (31–32). The overview culminates with Peter Brown and Robert Markus’ social and cultural approaches, which led to the view that the period was one of dynamic and even positive change, and the subsequent emergence of “Transformation of the Roman World” studies and reactions to them (9–11, 33–34).

After chapter three, Wood shifts to strategies for integrating the religious and secular histories of the period (34, 37–38). For example, in chapter seven, Wood suggests that concentrating on numbers, rather than culture and belief studies, facilitates fuller incorporation of the Church into the historical narrative (57). Using a quantitative approach to reformulate Gibbon's ideas on the impact of Christianity, Wood analyzes the logistical needs of the Church, such as the property, buildings, and the number of clergy required to function, not to argue that these were burdens that caused the fall of the western empire, but to understand why the Roman world was so transformed by the seventh century. While not necessarily novel in approach or results, Wood's presentation reinforces the difficulties of having to rely on numbers derived from scanty evidence in written sources, such as council meetings, and assumptions about how many clerics would be serving in various population areas, and then using these findings to make projections about “ordinary” dioceses (59–67).

Much of book focuses on assessing and responding to Gibbon's specific claims, primarily through secondary literature, some original primary source analysis, and the author's extensive knowledge of the period. For example, for the argument that “disorders of military despotism” contributed to the decline and fall of Rome, Wood examines various theories for the size of the military, its potential tax burden, along with the role of ambitious generals and usurpers (13–18). Wood agrees that the divisiveness men like Stilicho caused may have contributed to the empire's inability to deal with the “barbarians” and, as proposed by Gibbon, the “division of the monarchy” did exasperate the situation since Constantinople and Rome each had their own concerns (17–19).

Wood also takes on the contention that the rise of the clergy weakened the empire because “talented” men no longer chose careers in government and military service (84–85). Wood compares the numbers and distribution of soldiers and bureaucrats to monks and clerics to argue that while claims that elites chose religious vocations can be overstated, the influence of bishops, clerics and holy men did mark changes in the political structure (84–85, 87–88). For the successor kingdoms, Wood accepts that ecclesiastical leaders took on many functions previously associated with bureaucratic offices and served in the courts, using examples from Gregory of Tours and Visigothic church councils after 587 in what he consistently gives the problematic label, the “Spanish State” (85–87). Wood's intriguing suggestion that churches may have acquired additional property because the seventh century witnessed Europe's lowest level of military activity is not entirely convincing based on the evidence provided, such as the weapon-furnished burials, lack of ransoms in hagiographic texts, and the need to rebuild armies to combat the Muslims (81–83).

In chapter nine, Wood argues that the transfer of wealth to the church and its clergy was minimal before the sixth century, but by 700 over one-third of the lands of western Europe likely belonged to the Church. Therefore A.H.M Jones's “idle mouths” and Gibbon's “specious demands of charity and devotions” did not cause the collapse of the Roman state, but they certainly affected the kings of the sixth and specially the seventh centuries (91–92, 101–102, 105). Here, the emphasis on the social and economic implications of the expansion of the Church and its clergy is important, but the analysis is somewhat limited due to Wood's interest in responding to Gibbon.

Wood concludes that aspects of Gibbon's argument are easily refuted, such as the suggestion that the “barbarians” and Christianity caused the fall of Rome, and actually the failure to respond and not the migrations themselves proved catastrophic for Rome (22–28, 38–40, and 118). Even if Christianity cannot be blamed for Rome's collapse, over the course of the fourth through seventh centuries, religion and the church did transform the West and its economy and dominated most aspects of life by the end of the period (28, 109–110, 119–120). While perhaps not ground-breaking, this conclusion allows Wood to critique Carolingian studies and propose Charlemagne did not represent something novel, but rather an effort to revitalize a dynamic Charles Martel had dismantled (119). Overall, Wood's synthesis is impressive, engaging and informative. The evidence presented can appear cursory or anecdotal at times, but the analysis is not. Only someone with Ian Wood's expertise could produce a book this expansive in scope and concise in presentation. With the foundation Wood has provided, scholars can continue to integrate social, economic, political, cultural, and religious approaches and ask new questions that move us away from paradigms created in the eighteenth century.