The Decipherment, Step by Step

The Rosetta Stone gave the same decree in Greek, in demotic and in hieroglyphs, and it did not by itself unlock the script. Thomas Young had already shown that the cartouches held royal names and that those names were written with signs used for their sounds, which was real progress, but it left the assumption in place that phonetic writing was a device reserved for foreign words: Greek and Roman names had to be spelled out, while Egyptian was thought to be written in symbols standing for ideas.

Champollion broke that assumption in 1822 by applying the same reading to cartouches of native kings copied from Abu Simbel and elsewhere. Taking the sign of the sun, whose name he knew from Coptic as re, followed by signs he could already read, he arrived at Ramesses, and by a comparable route at Thutmose. That showed phonetic signs were being used for Egyptian words, which meant the script was mixed, phonetic and semantic together, and that it recorded a language rather than encoding concepts. He announced it in a letter addressed to the secretary of the Academy of Inscriptions and set out the system two years later. The key that made it work was Coptic, the descendant of Egyptian still in use as the liturgical language of the Egyptian church, which he had learned for the purpose.