Today in 1822, Jean-François Champollion presented to the Académie des Inscriptions et Belles-Lettres a draft of "Letter to M. Dacier concerning the alphabet of the phonetic hieroglyphs" explaining how he deciphered Egyptian hieroglyphs largely on the basis of the Rosetta Stone.
On September 14, 1822, Champollion made a crucial breakthrough in understanding the phonetic nature of hieroglyphs and proclaimed, "Je tiens l'affaire! " ("I've got it!") and then fainted from his excitement.
Champollion was the first Egyptologist to realize that some of the signs were alphabetic, some syllabic, and some determinative, standing for the whole idea or object previously expressed. He also established that the hieroglyphic text of the Rosetta Stone was a translation from the Greek, not, as had been thought, the reverse.