Sator square
A five-line Latin word square that reads the same in four directions, used as a protective charm.
Also: Rotas square, SATOR AREPO TENET OPERA ROTAS, magic square of words
The Sator square is a block of five Latin words, SATOR AREPO TENET OPERA ROTAS, which reads the same left to right, right to left, top to bottom and bottom to top. Examples have been found at Pompeii, which was buried in 79 CE, and in Roman sites across Europe and the Near East. Arepo is not a known Latin word, and no one knows what the whole line means. Some scholars see a Christian puzzle, since the letters can be arranged as a cross reading Paternoster twice, but the Pompeii finds make that doubtful. In the Middle Ages the square was inscribed on amulets and church walls to protect against fire and illness. It is now an object of puzzle and cryptography interest.