This "magic square" has been found scratched on walls throughout the Roman Empire, in places like Cirencester in England, Pompeii, and Dura-Europos in Mosopotamia. The letters spell the same words backward and forward, up and down. The exact meaning remains unsolved. Here it is:
ROTAS
OPERA
TENET
AREPO
SATOR
The individual words in Latin all have obvious meanings, but seem unrelated. Taken together, does the magic square have a meaning or message? If there is a meaning, it has never been deciphered.
