Rosetta Stone

The Rosetta Stone in 1985 at the British Museum.

In colloquial English, a Rosetta stone is any kind of key that can be used to translate across multiple domains of knowledge, as exemplified by the name of the scientific article Physics, Topology, Logic and Computation: A Rosetta Stone. The phrase refers to the Rosetta Stone, a large rock slab found in 1799 by French soldiers serving under Napoleon near the Egyptian port city of the Nile Delta named Rosetta (modern-day Rasheed). Engraved on the slab were parts of an ancient proclamation shown in two languages (Greek and Egyptian) and three scripts (Greek, Egyptian demotic, and Egyptian hieroglyphs. Since Egyptian hieroglyphs had not been readable by linguists before the discovery of the stone, these side-by-side scripts enabled linguists later to understand hieroglyphs on many other artifacts from ancient Egypt.

The Rosetta Stone carries an inscription of an Egyptian decree of 197 BCE honouring the king Ptolemy V Epiphanēs (205-180 BCE). The inscription comprises 54 lines in classical Greek that is repeated in two forms of Egyptian: 14 lines of hieroglyphics (‘picture-writing’) and 32 lines of demotic, the simplified form of hieroglyphic in common use. The stone was discovered about 65 km (40 mi) east-northeast of Alexandria, while digging the foundations for a fort (Fort St. Julien). The Rosetta Stone was captured by the British in 1801 and has been displayed in the British Museum since 1802.

The discovery of the stone made possible the eventual deciphering of hieroglyphics. Deciphering the hieroglyphs was begun by the English scientist Thomas Young (1773-1829), who isolated the proper names in the Demotic version (he showed that in this section, the name Ptolemy was rendered phonetically). The deciphering was completed by the French scholar Jean-François Champollion (1790–1832), who recognised that some of the symbols represented consonants, while others represented pairs of consonants. For example, Champollion determined that the first symbol in the name Ramses, the sun disc, represented the sound 'ra', after the sun god Rah.

Here is an excerpt of the text inscribed on the stone, rendered into English:

"It has seemed fitting to the priests of all the temples of Egypt, as to the honours which are due to King Ptolemy, living forever, the Manifest God whose excellence is fine, in the temples, and those which are due to the Father-loving Gods, who brought him into being, and those which are due to the Beneficent Gods, who brought into being those who brought him into being, and those which are due to the Brother-and-Sister Gods, who brought into being those who brought them into being, and those which are due to the Saviour Gods, the ancestors of his ancestors, to increase them; and that a statue should be set up for King Ptolemy, living forever, the Manifest God whose excellence is fine - which should be called 'Ptolemy who has protected the Bright Land', the meaning of which is 'Ptolemy who has preserved Egypt' - together with a statue for the local god, giving him a scimitar of victory, in each temple, in the public part of the temple, they being made in the manner of Egyptian work; and the priests should pay service to the statues in each temple three times a day, and they should lay down sacred objects before them and do for them the rest of the things that it is normal to do...."

--extract from the English translation, by R.S. Simpson (1996).

The Stone, though often described wrongly as black basalt, is granodiorite rock, dark grey-bluish-pinkish in color. It is 114.4 cm high at its tallest, 72.3 cm wide and 27.9 cm thick, and weighs about 760 kg.