On this day in 1822, Jean-Francois Champollion announced that he had deciphered the Rosetta Stone, 23 years after its discovery. The Rosetta Stone records a 196 BC decree from the reign of King Ptolemy V Epiphanes of Egypt, and it’s written in 3 different languages. That made it the key to translating ancient Egyptian hieroglyphs, as well as the Egyptian demotic script. The bottom language was Ancient Greek, which was well-known in the 1800’s, and the demotic and hieroglyphic scripts were inscribed above. So Campollion used the ancient Greek version of the decree to translate the other two, giving historians the key to reading hieroglyphs and demotic script on temple walls, ancient manuscripts, and everywhere else. Much of what we know about the ancient Egyptians—including those from far before 196 BC—comes to us thanks to Campollion’s work.