One of the most famous recurring miracles — even if one not quite sanctioned by the Catholic Church — is the liquefaction of the dried blood of San Gennaro, or St. Januarius, a bishop of Naples martyred around 305 A.D. and the city’s patron saint. Starting in 1389, the vial of San Gennaro’s blood typically turns liquid three times a year: on the Saturday before the first Sunday of May; on his saint’s feast day, Sept. 19; and on Dec. 16, the day Mt. Vesuvius erupted in 1631. The blood liquefied on Sept. 19 this year, but not on Dec. 16. “In local lore, the failure of the blood to liquefy signals war, famine, disease, or other disaster,” Catholic News Agency reports.