The Rosetta Stone: How One Rock Deciphered Ancient Egyptian Hieroglyphics

For 1,400 years, nobody on Earth could read hieroglyphics. The last person who understood them likely died in the closing decades of the Roman Empire, when Egyptian temples were shut and the priestly tradition that preserved the script was extinguished. Then a French soldier named Pierre-Francois Bouchard found a slab of granodiorite in the mud near Rashid (Rosetta), Egypt, in July 1799.

The stone carried the same decree in three scripts: hieroglyphic Egyptian, Demotic Egyptian, and ancient Greek. Scholars could read the Greek. The other two scripts were dead. In theory, the solution was straightforward: match the known text to the unknown. In practice, it took 23 years and one of the most obsessive scholars in history to crack it.

You can experiment with the same principle of matching unknown symbols to known text using our Hieroglyphics Translator, which maps English letters to their phonetic hieroglyphic equivalents.

The Rosetta Stone was carved in 196 BCE during the reign of Ptolemy V Epiphanes, a boy-king of the Ptolemaic dynasty. The inscription is a priestly decree issued by a council of Egyptian priests in Memphis. It praises Ptolemy V for tax exemptions, temple donations, and other acts of generosity, and declares that the decree would be inscribed in three scripts: "sacred" (hieroglyphic), "folk" (Demotic), and Greek.

This trilingual format was standard for official Ptolemaic decrees. The stone itself is 112 cm tall, 75 cm wide, and weighs approximately 760 kg. It is made of granodiorite, a coarse-grained igneous rock similar to granite.

After Napoleon's forces discovered it in 1799, the stone changed hands following the Treaty of Alexandria in 1801, when British forces defeated the French in Egypt. The stone was transported to London and has been on display at the British Museum since 1802, where it is one of the most visited objects in the collection.

Egypt has formally requested its return. As of 2026, a petition organized by former antiquities minister Zahi Hawass has gathered approximately 350,000 signatures toward a target of one million, after which he plans to launch an international repatriation campaign. The British Museum maintains that the stone was legally acquired under the Treaty of Alexandria and should remain in London.

The decipherment involved two principal figures, and crediting only one of them is a historical error.

Thomas Young (1773-1829) was a British polymath who had already made contributions to optics (the wave theory of light) and physiology before turning his attention to the Rosetta Stone in 1814. Young focused on the cartouches, the oval rings that enclose groups of hieroglyphic signs. He correctly deduced that cartouches contained royal names. By matching the Greek text's repeated mention of "Ptolemy" to a recurring cartouche, he identified the phonetic values of several hieroglyphic signs. He published his findings in the Encyclopedia Britannica in 1819, having defined 218 Demotic words and linked them to approximately 200 hieroglyphic signs.

Young's breakthrough stalled because he refused to believe hieroglyphs could represent sounds outside of foreign names. He thought the rest of the script was purely symbolic or ideographic.

Jean-Francois Champollion (1790-1832) was a French philologist who had been obsessed with ancient Egypt since childhood. By his teens he had mastered Latin, Greek, Hebrew, Arabic, Syriac, Chaldean, Chinese, and Coptic. The Coptic was the decisive advantage. Coptic is the final stage of the ancient Egyptian language, written in a modified Greek alphabet, and it survived as a liturgical language in the Coptic Church. Champollion's knowledge of Coptic allowed him to recognize Egyptian words where Young saw only symbols.

Champollion built on Young's cartouche work but took it further. He confirmed the phonetic reading of "Ptolemy" and then applied the same approach to the cartouche of "Cleopatra" from an obelisk at Philae. By comparing the shared letters between the two names (P, T, O, L, E), he validated his alphabet. His true eureka came in September 1822 when he examined the cartouche for "Ramses" and realized that the signs were phonetic, not symbolic, and that this was a traditional Egyptian name, not a foreign one. This meant hieroglyphs were not purely ideographic. They were a mixed system: some signs represented sounds (phonograms), some represented concepts (logograms), and some determined meaning (determinatives).

On September 27, 1822, Champollion announced his findings at the Academie des Inscriptions et Belles-Lettres in Paris. He published his Lettre a M. Dacier the same year, outlining the principles of the hieroglyphic writing system.

Champollion's decipherment revealed that Egyptian hieroglyphics use three types of signs:

Logograms represent whole words. The sign 𓊽 means "mountain," and 𓏏 means "bread."

Phonograms represent sounds. These are subdivided into uniliteral signs (one consonant, like an alphabet), biliteral signs (two consonants), and triliteral signs (three consonants). The uniliteral signs form what is sometimes called the hieroglyphic alphabet. For example, 𓄿 (vulture) represents the sound "A," 𓅓 (owl) represents "M," and 𓈖 (ripple of water) represents "N."

Determinatives are silent signs placed at the end of a word to clarify its meaning. The word for "house" (pr) might be followed by the determinative 𓉐 (a house plan) to indicate the word refers to a physical building, not a homophone with a different meaning.

Egyptian writing does not record vowels. This is why Coptic was so valuable to Champollion: it preserved the vocalic tradition of ancient Egyptian in a form that could be read. Without Coptic, reconstructing the pronunciation of hieroglyphic words would be far more difficult.

The script can be written left-to-right, right-to-left, or top-to-bottom. The direction is determined by which way the signs face: you read toward the faces of the human and animal figures. Royal names are enclosed in cartouches, which is why they were the entry point for decipherment.

The Rosetta Stone is, in cryptanalytic terms, a known-plaintext attack. The attacker (the decipherer) has both the ciphertext (the hieroglyphic and Demotic text) and the corresponding plaintext (the Greek text). The challenge is recovering the "key" (the mapping between signs and sounds).

This is the same principle that breaks classical ciphers. If you have a Caesar cipher ciphertext and you know one plaintext-ciphertext pair, you can compute the shift immediately. Our Caesar Brute Force tool does this by testing all 25 shifts at once, but with a known-plaintext pair, you only need one calculation: subtract the plaintext letter from the ciphertext letter, and the difference is the key.

The Rosetta Stone was not a perfect known-plaintext scenario. The three texts were not word-for-word translations of each other. The Greek and Egyptian versions had different grammatical structures, different word orders, and different ways of expressing the same decree. Young and Champollion had to find anchor points (like proper names in cartouches) and work outward from there.

For modern cryptanalysis, the lesson is that any cipher system where the attacker can obtain matched plaintext-ciphertext pairs is vulnerable. This is why modern encryption schemes like AES-GCM are designed to remain secure even when the attacker knows the algorithm and has access to chosen plaintexts. The security relies entirely on the secrecy of the key, not on the secrecy of the algorithm or the unavailability of plaintext-ciphertext pairs.

The Rosetta Stone is not a complete decipherment key. It provided the entry point, but reading Egyptian texts required years of additional work by Champollion and his successors. Many signs have multiple readings depending on context. The script evolved over 3,000 years, meaning Middle Egyptian (the classical form) differs from Late Egyptian, Demotic, and Coptic in grammar and spelling.

The phonetic values assigned by Champollion and later refined by scholars like Alan Gardiner in his Egyptian Grammar (1957) are approximations. We do not know exactly how ancient Egyptian was pronounced. The vowels are reconstructed from Coptic evidence and comparative linguistics, but there is ongoing scholarly debate about specific phonological details.

Our Hieroglyphics Translator uses uniliteral (alphabetic) signs from the Gardiner Sign List to map English letters to hieroglyphs. This is a simplified phonetic approximation, not a scholarly transliteration. Real Egyptian writing uses logograms and determinatives that a simple letter-to-sign mapping cannot capture.