The Rosetta Stone was the key that unlocked the mysteries of Egyptian hieroglyphics. It is a slab of black basalt dating from 196 BC. inscribed by the ancient Egyptians with a royal decree praising their king. The inscription is written on the stone three times, once in hieroglyphic, once in demotic, and once in Greek. From this we eventually managed to read most everything that remains of the Egyptians' ancient writings.