TWD S1E6 - Edwin Shows How a Walker Works
The Flood Hero Utnapishtim is granted immortality by The Gods and that fits the immortality theme of The Epic of Gilgamesh.
The main point seems to be that Utnapishtim was granted eternal life in unique, never-to-be-repeated circumstances.
As if to demonstrate this point, Utnapishtim challenges Gilgamesh to stay awake for six days and seven nights.
However, as soon as Utnapishtim finishes speaking Gilgamesh falls asleep.
Utnapishtim instructs his wife to bake a loaf of bread for every day he is asleep so that Gilgamesh cannot deny his failure.
Gilgamesh, who wants to overcome Death, cannot even conquer Sleep.
As Gilgamesh is leaving, Utnapishtim's wife asks her husband to offer a parting gift. Utnapishtim tells Gilgamesh of a boxthorn-like plant at the very bottom of the ocean that will make him young again. Gilgamesh obtains the plant by binding stones to his feet so he can walk on the bottom of the sea. He recovers the plant and plans to test it on an old man when he returns to Uruk.
Unfortunately, when Gilgamesh stops to bathe it is stolen by a serpent that sheds its skin as it departs, apparently reborn. Gilgamesh, having failed both chances, returns to Uruk, where the sight of its massive walls provokes him to praise this enduring work of mortal men.
The implication may be that mortals can achieve immortality through lasting works of civilization and culture.
