Liquefying blood relics

Did You Know?

• Francesco Paolo de Ceglia has argued that debates surrounding the blood of Saint Januarius reflected broader developments in early modern European thought regarding miracles and natural philosophy.
• Helen Hills has examined the role of the relic of Saint Januarius within the religious and artistic culture of Naples.

Major relics

The first recorded mention of Januarius's blood did not appear until a thousand years after his death. Tradition holds that his blood is kept in two sealed containers that become liquid during special services at Naples Cathedral. This liquefaction has been noted since medieval times and is a central part of Neapolitan religious life. Large crowds now gather at the cathedral three times each year to see it happen: on September 19, the saint's feast day marking his martyrdom; on December 16, celebrating his role as patron of Naples and its archdiocese; and on the Saturday before the first Sunday of May, which marks when his relics were reunited.

The Catholic Church has always backed these celebrations but has never issued an official position on the phenomenon itself, staying neutral regarding scientific study. Local belief also holds that a vial of Patricia of Naples's blood, kept at the Monastery of Saint Gregory Armeno in Naples, periodically becomes liquid. In Ravello, a relic linked to Saint Pantaleon is preserved; the material inside is said to liquefy each year and has often been compared to Januarius's relic.

Alphonsus Liguori wrote that he personally saw this vial in Ravello, where the blood turns liquid annually on the saint's feast day, appearing mixed with milk. Another relic, said to be the blood of Saint Lawrence, is kept in Amaseno, where local tradition says it liquefies during festivities for the saint's feast day.

Scientific explanations

Scientists have offered natural explanations for how these blood relics could liquefy. One is thixotropy, where a gel turns to liquid when shaken, a process feasible with medieval materials. In 1981, physicist Henri Broch replicated the effect using vegetable oil. Another possibility is the melting of substances with low melting points when warmed. Skeptic James Randi pointed out that many similar blood cults ended by the 1500s, suggesting local craftspeople or alchemists once possessed a secret method for creating such relics. The Church has generally prevented researchers from studying them.