To Christian missionaries from the pre-modern period, demons lurked behind every unfamiliar rock and tree, waiting to derail their best efforts. This was as true in late antique Europe as it was more than a thousand years later in sixteenth-century America. What is more, as Daniel Reff demonstrates in his most recent monograph, they were right. But the demon lurking both in pre-Christian Gaul and pre-Christian New Spain was not Satan but rather the plague of smallpox, and rather than derailing missionary activity, massive smallpox epidemics actually seem to have amplified missionary efforts and catalyzed the breakout success of the new religion as it was first introduced to both continents.

Reff's juxtaposition of the conversion of “Germanic” pagans in second- through seventh-century Europe and the conversion of Mesoamerican pagans in sixteenth-century Mexico proceeds along two fronts. His first proposition is that the spread of epidemic disease was crucial to the meteoric expansion of the Christian faith both in Late Antique Europe and in post-Columbian America. Reff further argues that the Jesuits tasked with the conversion of New Spain explicitly saw themselves as the heirs of their earlier European forbears, borrowing the “metaphors and epithets” (p. 207) of earlier Christian literature as well as their missionary mindset in a potentially hostile, pagan land. Both factors combined to speed the growth of the Christian church into areas where it had been previously unknown.

By drawing such a disparate comparison between Late Antique Europe and pre-modern America, Reff opens himself up to the obvious criticism about dissimilarities between these processes and the shortcomings of his primarily ecclesiastical sources. Reff parries these arguments by towing a middle line between post-structuralist “disintrest in human agency” (16) and “reductionist functionalism” (26) in favor of a “creativist” approach which attempts to consciously reconstruct the “pretextual reality” more or less faithfully described by the sources, as well as “other story lines … besides the author's own will to truth” (25). In this way, Reff exposes evidence for catastrophic demographic collapse due to smallpox epidemics in the years immediately preceding the widespread flowering of Christian evangelism in Europe and America. Although Reff imagines that pagans on both continents would likely have developed a “wholly native response” (177) to the social and economic effects of the epidemics, Christian missionaries in both contexts found themselves auspiciously positioned to promote their cults in the wake of disease, owing to the Christian church's organizational strengths and practical focus on care for the sick.

Any comparison between such widely separated places and events is bound to contend with the imbalance of solid anthropological or epidemiological data from late antique Gaul compared to post-Columbian Mexico, as well as the differing speeds at which events unfolded. However, by striking such a potentially audacious parallel, Reff's book re-conceptualizes the complex relationship between disease, memory, and salvation that has facilitated the extraordinary spread of Christianity in diverse circumstances from ancient Galilee to today's “developing” world.