“The way I always heard it told is that the lines of a prophecy work like the ridges and the notches of a key. A number of prophetic lines are strung together by a diviner, and then they are carved into a door—or, in this case, an arch. Once this is done, the arch will remain locked until each line of the prophecy has been fulfilled to create the key that will allow the arch to be opened again. It’s rather ingenious. If done well, a prophecy can ensure something stays unopened for centuries.”
