Steinbeck was quite insightful in bringing out the idea of George telling Lennie that if there was any trouble, he was to "go and hide in the brush." This was introduced in the opening, when things were tough, but not as complex. It was also introduced at a moment where hope was emerging to its zenith. The dream of the farm had already been introduced, and both Lennie and George had already been depicted to be different than others of the time period in their sense of community and shared experience with one another. In bringing both back to the brush at the end, Steinbeck has been able to bring a sense of the complete to the narrative:
The most important symbol in the novel is the bank of the Salinas River, where the novel begins and ends. In the story's opening, when George and Lennie come to the riverbank, it serves as a symbol of retreat from the world to a natural state of innocence. In this first scene, George tells Lennie that he should return to this riverbank if there is trouble at the ranch where they plan to work. The riverbank is a "safe place" for the two characters.
The fact that both the opening and ending begins with a naturalist view of the small pond is meaningful. At the start, Lennie and George were concerned with drinking water and whether it was "clean." Now, their situations have grown in complexity and their problems are much more intense. I think that Steinbeck brings out this intricacy in Lennie, himself. The vision of Aunt Clara and the rabbit from his own mind help to enhance the fact that the world is having an adverse effect on Lennie. Additionally, Lennie's refrain of "going into a cave" is challenged by his visions, suggesting that he would have never had the strength to leave George. In the end, the narrative comes full circle because of ending it where it starts. There is almost a Classically tragic feel to it, almost as if Steinbeck is giving his characters a sense of regal nobility that the real world would never grant to them. In this light, Steinbeck himself might be doing right what the world had done intensely wrong.