From House of Leaves by Mark Z. Danielewski

A monk joins an abbey ready to dedicate his life to copying ancient books by hand. After the first day though, he reports to the head priest. He's concerned that all the monks have been copying from copies made from still more copies.
"If someone makes a mistake," he points out. "It would be impossible to detect. Even worse the error would continue to be made."
A bit startled, the priest decides that he better check their latest effort against the original which is kept in a vault beneath the abbey. A place only he has access to.
Well two days, then three days pass without the priest resurfacing. Finally the new monk decides to see if the old guy's allright. When he gets down there though, he discovers the priest hunched over both a newly copied book and the ancient original text. He is sobbing and by the look of things has been sobbing a long time.
"Father?" the monk whispers.
"Oh Lord Jesus," the priest wails. "The word is 'celebrate.'"