Haldon's book attempts to tackle a simple, yet monumentally challenging question. Given the myriad existential challenges facing the Byzantine empire in the seventh century, how did the empire manage to hold on? In the introduction, Haldon notes five sets of factors that may have contributed to the survival of the Byzantine polity: "The role of beliefs and identity, the nature of the empire's elites, strategic geography, climate and environment, and organizational factors." These factors are then dealt with thematically for the remaining chapters of the book. It is phenomenally well researched and Haldon does a fairly good job of explaining much of the technical things like the climatic research and geographical aspects. My only qualm is that there could have been more done to tie everything together than the short conclusion at the end. There is a lot of information being covered here and it is easy to lose sight of the overarching topic. The thematic organizational structure was probably the best way to tackle this question, but better summaries at the end of chapters and relating information to things covered in previous chapters may have helped. Overall, though, it is a fascinating work and a must read for anyone interested in late antique or Byzantine history.