One of the most incredible pieces of literature I've ever read is Merlin's prophecy. The excerpt below is translated from Old British into Latin by Geoffrey of Monmouth, translated then from Latin into modern English by Norma Goodrich.
"To this spot a damsel from the white grove to take care of healing. After she shall have tried her arts, by her breath alone, she shall dry up the injurious springs. Then as soon as she shall have refreshed herself with the healing water, she shall bear in her right hand the Caledonian Forest, and truly in her left hand the warrior walls of Lothian. Wherever she shall set her feet down, her footsteps will burn with sulphur and smoke with two flames.
The fumes shall excite the Ruteni and make heat for those who live under the sea. She herself shall shed tears for those suffering; she will fill the island with horrid screaming.
The stag with ten branches shall slay her, four of his antlers crowned in gold..."
This prophecy (or poem) is the origin of the image of a battle between a red and white dragon. It is a long read, but well worth the time. I have come back to it again and again over the years, enjoying it more each time as I approach it with more understanding.