San Gennaro was martyred at Pozzuoli, just outside Naples, in 305 AD under the purges of Diocletian. Tradition has it that, when his body was transferred to Naples’ Duomo, two phials of his dried blood liquefied in the bishop’s hands, since which time the “miracle” has continued to repeat itself no fewer than three times a year – on the first Saturday in May (when a procession leads from the church of Santa Chiara to the cathedral) and on September 19 and December 16. The miraculous liquefaction takes place during a special Mass in full view of the congregation – a service it’s possible to attend, though the church authorities have yet to allow any close scientific examination of the blood or the “miraculous” process.
There is still a great deal of superstition surrounding this event: San Gennaro is seen as the saviour and protector of Naples, and if the blood refuses to liquefy – which luckily is rare – disaster is supposed to befall the city. Until recently, the last time that the blood liquefaction was witnessed by a pope was during Pope Pius’ visit to Naples in 1848. However, in March 2015, Pope Francis was present for the miracle – though the blood only half liquified (perhaps because the pope’s visit was outside the usual liquefaction dates). “We can see the saint only half loves us”, quipped the Pontiff.