The Liquefaction of the Blood
Although there is no definitive answer to the question of why the blood relics of Naples liquefy, it can be established that these liquefactions are roughly correlated with a number of variables. These rough correlations, I think, can at least provide us with some clues as to the identity of the different processes that produce the real or apparent liquefaction of these relics.
It would be naive to overlook the possibility that the liquefaction of these relics is the result of deliberate deception. The suggestion, often made, that trickery is unlikely since the clerics in charge of these relics have been men honestly committed to serving God is unconvincing. Throughout the history of the Church there have always been men and women who were quite sincere in their desire to serve God and yet who for that very reason felt no compunction about, say, exaggerating the reports of a miracle in order to bring people closer to God.
The best reason for rejecting the trickery hypothesis, at least as an explanation for the vast majority of liquefactions, was given by Thurston ( 1909a, 803-4): over the centuries too many people have been involved in administering these liquefactions. Even apart from the clerics who have administered the St Januarius cult at the Tesoro for the past six hundred years, for instance, in the last century or so the actual ceremonies have been administered by local civic officials as well. Add to this the clerics who have administered the ceremonies surrounding the blood relics at other locations, and the number is easily in the thousands. If there was a trick to the liquefaction of a blood relic, it seems likely that one of these people would have revealed it.
Moreover, there are instances in which a single church maintains several liquefying blood relics, some of which stop liquefying while others of which continue to liquefy. A good example involves two of the blood relics associated with John the Baptist. Both relics were liquefying in the sixteenth century, and both ended up at San Gregorio Armeno. The first came to San Gregorio Armeno from San Arcangelo at Baiano in