Archaeologists working near the amphitheatre of Emperor Hadrian’s Villa in Tivoli, Italy, have uncovered a marble slab dating back nearly 1,900 years that is dedicated to Summanus, the ancient Roman deity associated with nighttime lightning. The discovery sheds light on Roman religious practices concerning lightning and offers new insights into ancient interpretations of natural phenomena.
The slab, preserved in its original buried position, bears the inscription “FVLGVR SVBMANIVM,” which translates to a dedication to Summanus, distinguishing this god from Jupiter, who was associated with lightning during the daytime. This differentiation underscores the Roman belief that the timing of lightning carried specific divine significance.
Ancient Romans viewed lightning not merely as a weather event but as a sacred sign marking the presence of gods entering the human realm. When lightning struck, the affected area was considered permanently hallowed ground. Priests would collect any scorched earth or lightning-related debris and bury it onsite, effectively entombing the bolt itself. This ritual reflected the reverence held for these celestial occurrences and the deities believed to govern them.
Historical understanding of lightning by the Romans also included the notion that Jupiter launched physical thunderbolts from the sky, which caused storm destruction. Rather than lightning itself, these thunderbolts were seen as the agents of damage. The Roman orator Cicero referenced the phrase “condere fulmina,” meaning “to dig up thunderbolts,” a phrase that may hint at early recognition of fulgurites—naturally occurring glass tubes formed when lightning strikes sandy soil.
Fulgurites are created when the intense heat of a lightning strike—reaching temperatures around 30,000 degrees Celsius, several times hotter than the surface of the sun—fuses sand into hollow, glassy tubes with branching, root-like exteriors. These structures trace the path of the lightning discharge underground, sometimes extending up to 17 feet beneath the surface, effectively capturing a “fossil” record of the strike.
The recent find at Hadrian’s Villa highlights the intersection of natural phenomena and religious belief in ancient Rome, emphasizing the historical significance the civilization attributed to lightning. As excavations continue around the imperial complex, further discoveries may deepen understanding of Roman religious traditions and their engagement with the natural world.