13. By the water of babylon by stephen vincent benet

Wasn't this answered before?

"There was the great river below, like a giant in the sun. It is very long, very wide. It could eat all the streams we know and still be thirsty. Its name is Ou-dis-sun, the Sacred, the Long. No man of my tribe had seen it, not even my father, the priest. It was magic and I prayed."

From text