Why did the Greek text on the Rosetta Stone help scholars decipher Egyptian hieroglyphs?

The Rosetta Stone was instrumental in deciphering hieroglyphic writing because it contained the same text inscribed in three different scripts: hieroglyphics, demotic script, and the Greek alphabet.12

Because the Greek text was readable, it served as a vital reference point for scholars like Thomas Young and Jean-François Champollion. By comparing the known Greek text to the unknown Egyptian signs, researchers were able to identify proper names—specifically royal cartouches—and eventually establish the phonetic values of the hieroglyphs. Champollion ultimately determined that the hieroglyphic text was a translation of the Greek, allowing him to create a comprehensive list of signs and their equivalents, which unlocked the ability to translate ancient Egyptian texts.12