The aim of Francesco Paolo de Ceglia's research is to shed light on the way in which eighteenth-century science examined a particular category of miracles which were very common in the Kingdom of Naples in the modern age. These are the so-called “perennial miracles,” characterized, in comparison with “normal” or “episodic” miracles, by a certain periodicity or, in any case, by being repeated in particular circumstances. These characteristics made the mention of these miracles a very important subject in the Catholic apologetic literature. In fact, the Church of Rome could boast of having to its credit miracles subject to a sort of “supernatural normativity.” On the other hand, however, these same characteristics meant that the perennial miracles could be more systematically studied by the men of science of the age, many of whom, in particular Protestants and Libertines, approached them with great suspicion and extremely high level skills.
In particular, the Kingdom of Naples had seethed with “liquid miracles” since the Baroque Age. First of all, the capital itself, the city of Naples, could count, with an exceptional concentration even for the time, the solidified blood of a couple of hundred martyrs. These blood relics seemed to have “intelligent” behaviors. Each one had its own “style.” In fact, they could return to the liquid state, change color, shine, or bubble on the occasion of particular liturgical celebrations, with certain prayers, with the reading of certain passages of the Gospel or near other parts of the body of the same saint. Then there was the so-called “manna:” the liquid—oily and highly scented—that oozed out of the bones of numerous saints, generally proto-Christian martyrs (from the East), buried here and there throughout the Kingdom. These were the “peripheral” perennial miracles, rather than the “central” blood miracles, which, as mentioned, were generally confined to the city of Naples and its immediate surroundings.