Starting in the late Middle Ages, rumors spread throughout Europe about blood miracles. These concerned first the alleged relics of Christ, then those of the martyrs, and finally those of many other saints. Black blood, usually pulverized or solidified over the centuries, was said to return to its original bright red color, or it liquefied or bubbled in certain circumstances or on certain dates on the liturgical calendar. With the Reformation, in Protestant countries most of those relics were destroyed or simply forgotten, although for a few centuries there were cases of unspecified blood wonders or prodigies that would be much discussed in an attempt to interpret them in natural terms. In Catholic countries, in contrast, the blood miracles multiplied, reaching a peak between the seventeenth and eighteenth centuries, when, even more than before (a fact never sufficiently emphasized by historians), they were used in apologetic literature.
This project aims to reconstruct the procedures with which, in the most heated moment of the debate, the properties of the ancient blood were tested and the results were made public, often not in publications but by staging highly theatrical demonstrations. These were initially semi-clandestine performances that then, in the century that saw the birth of modern conjuring, became actual touring shows, increasingly popular and illusionistic. I consider the time period from the last two decades of the seventeenth century, when problems arose regarding the identification of reddish substances found in newly discovered Christian catacombs, to the 1790s, when the first round of testing the behavior of the blood of Saint Januarius of Naples was completed.
Particular attention will be paid to the miraculous Neapolitan bloods—St. Januarius, St. John, St. Stephen, St. Patricia, etc. In the eighteenth century, these were studied by many scientists, who, throughout Europe (even in very Catholic Naples), developed recipes and equipment replicating their “intelligent” behavior. In a period when canonization processes were undergoing a rapid evolution leading to medicalization, many asked a question that was very tricky from both the theological and the scientific points of view: Does demonstrating that a behavior similar to the miraculous can be produced naturally or artificially imply that it is non-supernatural? In other words, what role does analogy play in testing phenomena that are in some way unique and unrepeatable?