Naples Cathedral — the blood of San Gennaro

OVERVIEW

Saint Januarius (San Gennaro) is the principal patron of Naples. Three times a year — the Saturday before the first Sunday of May, 19 September and 16 December — the faithful gather to watch the liquefaction of what is claimed to be a sample of his blood. It is held in two hermetically sealed ampoules in a 17th-century silver reliquary: a small one with a few reddish spots, and an almond-shaped one of about 60 ml, about 60% full of a dark reddish substance.

HISTORY

A Naples chronicle of 1382 describes the saint's cult in detail but mentions neither relic nor miracle; the first certain date is 1389, when the blood 'was found to have melted'. Over the next two and a half centuries official reports had it melt once, then twice, then three times a year. The archbishop holds up the reliquary and tilts it to show the contents solid, and after intense prayer — including by the 'relatives of San Gennaro' — tilts it again to show them liquid; it can take two minutes, hours or days. Failure is taken as an omen: it did not liquefy in September 1939, 1940, 1943, 1973 and 1980, or in December 2016 and 2020. It liquefied for Pius IX in 1848, not for John Paul II (1979) or Benedict XVI (2007), and 'half' for Pope Francis in 2015.

REPORTED ACTIVITY

The Church supports the celebration but has never made an official statement and does not allow the ampoules to be opened. Spectroscopy in 1902 and 1989 reported a spectrum consistent with haemoglobin; claims of a weight gain of up to 28 g (1900, 1904) were not confirmed by later precision weighing. Luigi Garlaschelli and colleagues reproduced the colour and behaviour with a thixotropic gel of hydrated iron oxide, makeable with materials available in the Middle Ages; Henri Broch did it with vegetable oil in 1981. In 2010 Giuseppe Geraci of Naples University showed an 18th-century blood relic from Camaldoli — and his own blood stored the same way — changing phase when shaken. The historian Francesco Paolo de Ceglia argues for a thermal cause: in September the 'blood' is often already liquid. James Randi noted that some twenty Campanian blood cults all appear in the same region from the same period.

VISITING

The ritual takes place in Naples Cathedral (the May one in procession to Santa Chiara). The Museum of the Treasure of San Gennaro, entered under the arcades on the right of the cathedral, gives access to the saint's chapel even when the cathedral is closed.