In the Prologue, the narrator uses hyperbole to describe Gilgamesh's intelligence:
This was the man to whom all things were known; this was the king who knew the countries of the world. He was wise, he saw mysteries and knew secret things, he brought us a tale of the days before the flood.
This quotation follows the narrator's opening announcement: "I will proclaim to the world the deeds of Gilgamesh." If the reader is already familiar with the story of Gilgamesh, the hyperbole is clear. Despite being wise and well-traveled, Gilgamesh does not know "all things." In fact, he is often unclear about the meaning of specific things (like his dreams), asks the gods for advice and assistance, and otherwise relies on the knowledge of others in the course of his adventures.
And yet, the hyperbole emphasizes the extent of Gilgamesh's wisdom despite being an exaggeration. Gilgamesh is the most well-traveled part-mortal in history: he visits, among other far-off places, the Garden of the Gods. In fact, Gilgamesh's greatest gift to his fellow man is writing down the knowledge of his adventures on tablets at the end of the story. Beginning the story with an instance of hyperbole emphasizing Gilgamesh's knowledge underscores the importance of wisdom and memory in a story that ends with the transcribing of history. Recorded history is also a fundamental pillar of civilization in a tale that explores the costs and benefits of moving from nature/the wild to cities/civilization. Finally, this is all particularly significant considering that The Epic of Gilgamesh is the oldest surviving story known to man. For the oldest surviving story to privilege knowledge and memory at its outset and conclusion is especially apt.