Lettre à M. Dacier
Lettre à M. Dacier (full title: Lettre à M. Dacier relative à l'alphabet des hiéroglyphes phonétiques: "Letter to M. Dacier concerning the alphabet of the phonetic hieroglyphs") is a scientific communication in the form of a letter sent in 1822 by egyptologist Jean-François Champollion to Bon-Joseph Dacier, secretary of the French Académie des Inscriptions et Belles-Lettres. it is the founding text upon which Ancient Egyptian hieroglyphics were first systematically deciphered by Champollion, largely on the basis of the multilingual Rosetta Stone.
While visiting his brother Jacques-Joseph on September 14, 1822, Champollion made a crucial breakthrough in understanding the phonetic nature of hieroglyphics, and proclaimed "Je tiens l'affaire!" ("I've got it!") and then fainted dead away.
On 27 September 1822, he exhibited at the Académie des Inscriptions et Belles-Lettres a draft containing eight pages of text to a packed room.