Mulberries have long been associated with wisdom. The fact that Eli vomits the mulberries suggests, perhaps, that he’s not the wise one here—August is. August is more like the boy in the story, who’s able to take mulberries and other things in, and then somehow make those things beautiful and meaningful. Slim seems to make this connection when he calls this boy the one “with all the answers,” which is something he’s also called August before.