Dendera: The Relief That Became an Ancient Lightbulb

Inside the Temple of Hathor at Dendera, Egypt, the temple crypts hold a relief showing a serpent inside a large oval object. The object rests on a djed pillar, with divine figures beside it appearing to support or present it. To a modern eye, the scene resembles a lightbulb: the serpent looks like a filament, the oval looks like a glass envelope, and the pillar looks like a base.

Dendera is not an isolated ruin. Most of the surviving Temple of Hathor was built under Ptolemy XII in the 1st century BCE and continued to be decorated under Roman emperors. Its walls carry hieroglyphs, ritual scenes, and the story of Harsomtus. The relief remains controversial because it can be read in two ways. One reading treats it as a religious image of a divine serpent emerging from a lotus. The other treats it as a coded record of a light-producing device whose method no longer survives.