What Is a Thunder God? The Same Figure in Unrelated Traditions

The figure arrives with a consistent set of attributes across widely separated traditions. He controls storms and throws lightning, frequently as a thrown weapon that returns or is inexhaustible. He is associated with rain and therefore with agricultural fertility, which makes him beneficial rather than merely destructive and explains why he is so often the god people actually petitioned. He is strong rather than clever, usually with an appetite and a temper, and frequently contrasted with a more calculating figure elsewhere in the pantheon. He fights and defeats a serpent or dragon associated with water, drought or chaos, and that combat is a central story rather than an incidental one. He is linked to oak trees, which is at least partly because oaks are struck by lightning unusually often. And he is associated with kingship and with oaths, so swearing by him carries weight.

The same outline appears with local detail across an enormous geographic range:

• •Thor in Norse tradition, with a hammer, a chariot and a running conflict with a world-encircling serpent
• •Zeus in Greek tradition, with the thunderbolt, supreme among the gods and having overthrown an earlier order
• •Indra in Vedic tradition, wielding the vajra and killing the serpent that withheld the waters
• •Perun in Slavic tradition, associated with oaks and opposed to a figure of the underworld and waters
• •Baal in Levantine tradition, storm god and rain bringer, in conflict with the sea and with death
• •Raijin, Shango, Chaac, Tlaloc and many others across Japanese, Yoruba and Mesoamerican traditions, each embedded in its own system and sharing recognisable features

Two explanations compete for the overlap and both are partly right. Common descent accounts for a substantial share, since the Norse, Greek, Vedic, Slavic, Baltic and several other traditions descend from a shared ancestral culture, and comparative linguistics reconstructs a storm deity with a weapon and a serpent opponent in the parent tradition, with some of the names themselves being cognate. That is real evidence rather than a loose resemblance, since sound correspondences between names are the same kind of evidence used to establish the relationship between the languages. It cannot explain the figures outside that family, and there the second explanation applies, which is that thunder is the most dramatic natural event most people ever witness, it is unpredictable, it arrives with life-giving rain and it kills, and a personified account of it will reach similar conclusions anywhere. The methodological difficulty is that both explanations predict similarity, so similarity alone does not choose between them.

The trajectory of these figures under religious change is revealing. Several were absorbed rather than eliminated, with attributes transferred to saints who inherited the storm associations, the oak connections and the feast days, which happened across Christian Europe and is documented in the overlap between the dates and the folklore. Others survived in folk practice long after official conversion, invoked against lightning and for rain by people who also attended church, and the names persisted in weekday names, place names and oaths. Some were demoted, with a former supreme deity recast as a demon or a giant in the traditions that replaced them. The combat myth proved particularly durable, since a hero defeating a dragon transfers easily into new religious frameworks and reappears with saints and knights in the role. That persistence suggests the figure was meeting a need that survived the theological change that was supposed to remove it.

The prominence of storm deities specifically, rather than gods of other natural forces, has a plausible practical basis. Agricultural societies depend on rain and are destroyed by its absence, so the power that supplies or withholds it matters more than almost anything else, which explains both the prominence and the strong association with fertility. The combat with a serpent hoarding water maps directly onto drought, and the story of the god releasing the waters is a story about the return of rain, which makes it worth telling annually. Lightning is also the clearest available evidence of a power acting from the sky, being visible, sudden and lethal, and it produces immediate physical effects including fire, which supports an interpretation in terms of a weapon. And the association with kingship follows, since a ruler claiming legitimacy benefits from association with the most obviously powerful figure, which is why so many royal houses claimed descent from one.

The figure arrives with a weapon, control of rain, an oak association, a serpent to fight and a link to kingship, across traditions with no contact. Shared descent explains the Norse, Greek, Vedic and Slavic versions, with some names being genuinely cognate, and cannot explain the rest. Thunder being the most dramatic event anyone witnessed accounts for the others, and similarity alone cannot choose between the two explanations.