The Rosetta Stone records a decree in Egyptian hieroglyphs, Demotic, and Ancient Greek. The known Greek text helped scholars study the other scripts.
Discovered in 1799, the stone provided important clues for deciphering Egyptian writing. The process still required comparisons with other documents and inscriptions.
Memphis decree and its context
The stele was erected after the coronation of King Ptolemy V and was inscribed with a decree that established the divine cult of the new ruler. The decree was issued by a congress of priests who gathered at Memphis. The date is given as "4 Xandikos" in the Macedonian calendar and "18 Mekhir" in the Egyptian calendar, which corresponds to 27 March 196 BC.
The year is stated as the ninth year of Ptolemy V's reign (equated with 197/196 BC), which is confirmed by naming four priests who officiated in that year: Aetos son of Aetos was priest of the divine cults of Alexander the Great and the five Ptolemies down to Ptolemy V himself; the other three priests named in turn in the inscription are those who led the worship of Berenice Euergetis (wife of Ptolemy III), Arsinoe Philadelphos (wife and sister of Ptolemy II), and Arsinoe Philopator, mother of Ptolemy V. However, a second date is also given in the Greek and hieroglyphic texts, corresponding to 27 November 197 BC, the official anniversary of Ptolemy's coronation. The demotic text conflicts with this, listing consecutive days in March for the decree and the anniversary.
Greek text
The Greek text on the Rosetta Stone provided the starting point. Ancient Greek was widely known to scholars, but they were not familiar with details of its use in the Hellenistic period as a government language in Ptolemaic Egypt; large-scale discoveries of Greek papyri were a long way in the future. Thus, the earliest translations of the Greek text of the stone show the translators still struggling with the historical context and with administrative and religious jargon. Stephen Weston verbally presented an English translation of the Greek text at a Society of Antiquaries meeting in April 1802.
Meanwhile, two of the lithographic copies made in Egypt had reached the Institut de France in Paris in 1801. There, librarian and antiquarian Gabriel de La Porte du Theil set to work on a translation of the Greek, but he was dispatched elsewhere on Napoleon's orders almost immediately, and he left his unfinished work in the hands of colleague Hubert-Pascal Ameilhon. Ameilhon produced the first published translations of the Greek text in 1803, in both Latin and French to ensure that they would circulate widely. At Cambridge, Richard Porson worked on the missing lower right corner of the Greek text. He produced a skillful suggested reconstruction, which was soon being circulated by the Society of Antiquaries alongside its prints of the inscription.
Hieroglyphic text
Silvestre de Sacy eventually gave up work on the stone, but he was to make another contribution. In 1811, prompted by discussions with a Chinese student about Chinese script, Silvestre de Sacy considered a suggestion made by Georg Zoëga in 1797 that the foreign names in Egyptian hieroglyphic inscriptions might be written phonetically; he also recalled that as early as 1761, Jean-Jacques Barthélemy had suggested that the characters enclosed in cartouches in hieroglyphic inscriptions were proper names. Thus, when Thomas Young, foreign secretary of the Royal Society of London, wrote to him about the stone in 1814, Silvestre de Sacy suggested in reply that in attempting to read the hieroglyphic text, Young might look for cartouches that ought to contain Greek names and try to identify phonetic characters in them.
Young did so, with two results that together paved the way for the final decipherment. In the hieroglyphic text, he discovered the phonetic characters p t o l m e s (in today's transliteration p t w l m y s) that were used to write the Greek name Ptolemaios. He also noticed that these characters resembled the equivalent ones in the demotic script, and went on to note as many as 80 similarities between the hieroglyphic and demotic texts on the stone, an important discovery because the two scripts were previously thought to be entirely different from one another. This led him to deduce correctly that the demotic script was only partly phonetic, also consisting of ideographic characters derived from hieroglyphs. Young's new insights were prominent in the long article "Egypt" that he contributed to the Encyclopædia Britannica in 1819. He could make no further progress, however.