Let's get this out of the way fast: we don't mean "earth" as in "Planet Earth." After all, given that Gilgamesh goes beyond the edge of the world into a mysterious underworld, it's pretty clear that the ancient Mesopotamians did not think about the world as a planet the way we do. No: what we're talking about is "earth" as a substance, earth as in stuff, earth as in dirt, dust, and clay.
Especially clay. Clay comes up again and again in the epic as the substance from which living things are made, and into which they decay once they die. Thus, it is a symbol of both life and death. You could say that it is also a symbol of human limitations: like it or not, we're made of clay. And in Gilgamesh, we mean that literally.
After the citizens of Uruk make their prayer to Anu for help against Gilgamesh's tyranny, he delegates solving the problem to Aruru, the goddess who created humans. And she hops to it: "Aruru washed her hands, she pinched off some clay, and threw it into the wilderness" (1.83). Then, presto-changeo, the clay turns into Enkidu, the wild man of the wilderness! (There must be some other steps involved here, but clay is still the basic substance.)
So we know for a fact that Enkidu is made of clay. Thus, after Enkidu has died, one of the details that Gilgamesh keeps obsessively repeating in his lamentations for his friend is how "my friend whom I love has turned to clay" (10.71). And, just in case you were thinking, "Hey, we only saw Enkidu get made out of clay; maybe Gilgamesh is made out of something else," Gilgamesh continues: "Am I not like him? Will I lie down, never to get up again?" (10.72).
Not if you turn into clay, you won't.
Another vivid example of clay symbolism comes up in Enkidu's dream of the underworld from Tablet 7, which we already talked about under the theme of "Food," above. In Enkidu's dream, he imagines all the dead people sitting around, wearing feathers (yeah, we don't know what that's all about either), "where dirt is their drink, their food is of clay." (7.179).
We guess if you're dead and in the underworld, dirt might just be a very refreshing drink. But Enkidu doesn't want to leave any potential earth symbolism out. Thus, in his description of the underworld, he also says that, at the entrance to the land of the dead, "upon the door and bolt lies dust," and, in the next line, he actually refers to the underworld as "House of Dust." (7.183)
Even the gods get on the bandwagon in Tablet 11, when they are complaining about how the great Flood has destroyed all life on earth; from out of the huddle of cowering gods, Ishtar exclaims, "The olden-days have alas turned to clay." (11.118)
The point here is that even though Gilgamesh is doing all he can to outrun death, we all know he can't. Eventually all of us (no, really, all of us, and that means you too) are going to become dust again. Here at Shmoop, this makes us think of Genesis 3:19—also a text from some Mesopotamian peoples: "By the sweat of your brow you will eat your food until you return to the ground, since from it you were taken; for dust you are and to dust you will return."
So, get ready; we all have some dust in our futures. But, Gilgamesh at least helps us see that we can make our journey to dust worthwhile.