Fourteen centuries, give or take, in which nobody could read them. The last dated hieroglyphic inscription is late fourth century, and after that the signs went quiet and stayed pictures to everyone who looked at them. That was the trouble, really — the assumption that each little owl and reed and seated man stood for a whole idea, mystically and entirely. Athanasius Kircher filled beautiful folios with that assumption in the 1600s, at length and in good faith. What Champollion read out to the Académie in Paris in 1822, in a letter addressed to Dacier, was that the signs spelled as well as depicted: sounds, names inside those oval cartouches, writing that worked the way writing works.
I've had more confident wrong keys to Egypt through the shop than right ones; they're handsomer books, mostly, and they sell. The stone itself is in one of the pictures here, the top edge broken off, three bands of script running down it — hieroglyphs, then the cursive, then the Greek that let the door open.
And the text that broke it open is, as far as we know, administrative housekeeping: a synod of priests at Memphis in 196 BC agreeing on honours for Ptolemy V, who was a boy of about twelve. Tax relief, temple revenues, a resolution that copies be set up in three scripts. A committee minute, and it carried fourteen centuries on its back.
Cartouche is a borrowed word, Jun — French soldiers in Egypt thought the oval rings looked like paper gun cartridges, and the nickname stuck hard enough that Egyptologists still use it. So a pharaoh's name sits inside a bit of army slang.
Jun, the stone's granodiorite, hard grey stuff, and the carver of the Greek at the bottom clearly ran out of room — look at how the letters crowd and the lines tighten as they go down. Somebody in Memphis in 196 BC measuring badly, then compensating. Kircher's folios really are lovely to hold, whatever else they are.