The 20th of June is the commemoration of the enshrinement of Summanus, the god of nocturnal lightning and one of Rome’s oldest gods

At one time, Summanus was more popular than Jupiter. But by the time of Emperor Augustus, he had become a near-forgotten deity, whose past significance was lost and who eventually only survived in memory as a dark, underworld deity.

So who was Summanus? And why did the Romans venerate and then forget him?  

The Origins of Summanus.

The origin of Summanus’ name is obscure and subject to many theories. It may derive from the Latin preposition ‘sub’ combined with the noun ‘mane’ meaning ‘before the mourning’ — which is logical as Summanus was the god of nocturnal lightening.

According to Varro, the Romans adopted Summanus as a god of Rome at the time of Romulus. The Roman King and his Sabine ally, Titus Tatius, each instituted new cults. Romulus introduced the cult of Jupiter while Tatius “vowed altars to Ops, Flora, Vediovis and Saturn, Sun, Moon, Vulcan and Summamis, and likewise to Lariinda, Terminus, Quirinus, Vertumnus, the Lares, Diana and Lucina”.

 Pliny, in his Natural History, describes how the Etruscans recognized nine gods of thunder, of which Summanus was only one — suggesting the god’s origins were Etruscan. But Summanus could have been older still. Near Veneto in the Italian Alps is Mount Summano, a mountain associated with the cult of Summanus. The location of the mount just over the border of what was Etruscan territory suggests Summanus’s status was impressive enough for the Etruscan’s adopted the god from another people

But by the fifth century AD, Summanus’s name acquired an otherworldly connection. A writer of the period, Martianus Capella, believed the god’s name derived from ‘summus manium’ –‘highest of the Manes’, the Roman spirits of the dead and also gods of the underworld. This led to an association between Summanus and Pluto, the chief god of the underworld.

But originally, Summanus was associated with a very different god of the Roman pantheon.

Summanus: Jupiter’s Dark Twin.

According to Pliny, of the nine Etruscan lightening gods, the Romans kept only two: Summanus and Jupiter: 

“They attribute daytime thunderbolts to Jupiter, “stated the writer in his Natural History,” and ones at night to Summanus,”  

This description seems to suggest that at one point in their history, Summanus was the equal-and-opposite aspect of Jupiter.   An inscription from 224AD, cited by Beard, North and Price, describes the sacrifices offered to appease the gods after lightning destroyed several trees from the grove of Dea Dis, just outside Rome. Jupiter received two wethers or castrated rams. Summanus received an offering of the same beasts — but his wethers were black, to befit a nighttime god.  

Summanus’s Temple and Cult.

Little evidence remains of Summanus’s cult in Rome, but he must have been held in some regard and importance as a temple was dedicated to him on the 20th of June sometime between 275-278BC. The temple, located near the Circus Maximus, was erected during the war with Pyrrhus — not because of the conflict —but because, according to Fowler, lightening one night had destroyed a statue on the temple of Jupiter. 

This act of natural destruction seems to have convinced the Roman’s of the strength of Summanus. As a result, not only did the god gain a temple but every the 20th of June, the Romans pacified him with summanalia  — round cakes made of flour, milk and honey.  

The Forgotten God

Certain evidence suggests that — for a time — Summanus may have been held in higher regard in Rome than Jupiter himself. St Augustine states that:

 “The ancient Romans paid greater honours to I know not what Summanus, to whom they attributed nocturnal thunderbolts than to Jupiter.” 

But he then adds: 

…. But after a famous and conspicuous temple had been built to Jupiter, owing to the dignity of the building, the multitude resorted to him in so great numbers that scarce one can be found who remembers even to have read the name of Summanus.” (City of God, IV 23).

This description seems to tie in with events from 197BC described by Livy. Not only was a new temple to Jupiter constructed, but lightning struck Summanus’s temple (XXXII 29, 1). It may be a lightning strike on Summanus’s shrine suggested to the Roman people that the nocturnal god’s power was waning — and by this time, Jupiter had become head of the Roman pantheon,  a position strengthened by his association with the Greek Zeus. 

Whatever the reason, from that time onwards, Summanus seems to have been on the wane. By the early imperial period, he had become sufficiently obscure for Ovid to mark the 20th of June as   dedicated to “Summanus, whoever he is.” 

A Dark God?

If he was remembered at all, Summanus only survived as an adjunct trait of Jupiter. Later inscriptions mention, Jupiter Summanus as a nocturnal aspect of the Roman lightening god instead of a separate deity in his own right.

But Summanus survived in history with a darker reputation. In the sixteenth century, Martianus Capella’s association between Summanus and Pluto seems to have led the Portuguese poet Cameoes to associate Summanus with hell when he describes how: 

“If in Summanus’ gloomy realm / Severest punishment you now endure.”  

The God of Nocturnal Thunder and the Cycle of Life

This seems a sad end for the thunder god. For even though the function of Summanus as a god of lightning had mutated into an association with the chthonic and underworld deities in late antiquity, that does not mean he deserved an evil reputation. 

Originally, the chthonic deities were not sinister figures but part of the cycle of life. The dead returned to the earth — but the earth also gave life to plants and crops. So, even if Summanus had exchanged the sky for the underworld, he does not deserve to survive with such a gloomy fashion.

Sources

Augustine, The City of God 

Beard, M, North, J and Price, S, Religions of Rome, Vol 2,Cambridge University Press, 2005

Dumezil, G, (trans. Philip Krapp), Archaic Roman Religion, Vol I and II, The John Hopkins University Press, 1996

Livy, The Early History of Rome

Martianus Capella, De Nuptiis2.164.

Thomas Moore Musgrave, (trans) The Lusiad  (Camoes Os Lusíadas, IV, 33) 1826.

Ovid, Fasti

Pliny, Natural History

Varro, On the Latin Language

W Warde Fowler, The Roman Festivals at the Period of the Republic,Macmillan and co, 1899.