In chapter 18, Hurston uses setting to develop the theme that you do not truely appreciate what you have until there is a chance it could be taken away. Hurston does this by showing Janie and Tea Cake's reactions to the setting and the hurricane that will hit them soon. 

At the beginning of the chapter there are rumors that a huricane will be hitting the town Janie and Tea Cake live in. This rumor forced many people to flee the area,"Thank yuh ever so mych, Lias. But we 'bout decided tuh stay" (156). In this passage it is apparent that Tea Cake has no doubt in his mind that there will not be a storm hitting the muck. It is also apparent that Tea Cake would risk Janie's life because "de money's too good on the muck"(156), not because he does not love her but because he does not truely appreciate her. 

Then when the huricane comes to the muck Hurston describes the setting where there was "water almost to their buttocks"(161). Even though there was so much water and danger outside of the house Tea Cake knew that the only way he could save Janie was to leave the house and walk. Tea Cake comes to the realization of how much Janie truely means to him and how much he would risk for her right before they had to leave because of the hurricane. Janie says to Tea Cake that she loves him and that all the time she spent with him was worth being in a hurricane for, so he dropped to the floor and put his head in her lap. "Well then, Janie, you meant whut you didn't say, 'cause Ah never knowed  you wuz so satisfied wid me lak dat. Ah kinda thought-" (160). This emphasizes how much Tea Cake realized he truely loves Janie, but he realizes this in a time of danger in which all he cares for(Janie) could be taken away from him at any second. Which illuminates the theme that you do not truely appreciate what you have until there is a chance it could be taken away.