Enmerkar, the legendary ruler of Uruk (Unug-Kulaba), engaged in a protracted rivalry with the ruler of Aratta, a mythical city far to the east of Mesopotamia. The two rulers send messengers back and forth with increasingly complex riddles for one another to solve and thereby demonstrate one ruler's superiority over the other. During the third exchange Enmerkar's instructions to his messenger are beyond the capacity of his memory:

His speech was substantial, and its contents extensive. The messenger, whose mouth was heavy, was not able to repeat it. Because the messenger, whose mouth was tired, was not able to repeat it, the lord of Kulaba patted some clay and wrote the message as if on a tablet. Formerly, the writing of messages on clay was not established. Now, under that sun and on that day, it was indeed so. The lord...