In Steinbeck's novel, The Grapes of Wrath, Ma Joad and Rose of Sharon graphically portray the themes of strength and sacrifice. They are universal characters, the people who make up the fabric of society in every nation. Through them we understand the need for unity and we feel the desperation of the billions of laborers who struggle every day just to survive.
Throughout the story Ma is a model of the strength of the human spirit. For example, Steinbeck says of her, "if she swayed the family shook, and if she ever really deeply wavered or despaired the family would fall, the family will to function would be gone". She is the foundation upon which the rest of the family stands. Just as when a single driblet of dye is dropped into a glass of water and disperses throughout, her strength permeates to the rest of the family, infusing them with her mightiness. Also, when the Wilson's car breaks down and Pa proposes splitting up just for a short time until the car is repaired she threatens him with a jack handle. She knows that all they have in the world is each other and without each other to hold on to they have nothing. There is a saying "one finds comfort in numbers" however in this case "comfort" is replaced with survival. In addition, near the end of the book, when the boxcars have flooded and it seems all hope has been lost Ma leads the family to higher ground. Despite the despair she feels she overcomes it to do what must be done to insure that they survive to live another day. Her strength gives her the power rise above adversity and to be the leader that she is. Ma's strength is what allows the family to hold up as long as they do.
Rose of Sharon, on the other hand, shows the sacrifice the Joads and the rest of the Okies had to endure. For example, while they are driving to California she tells Ma of her and Connie's desire to live in a house with a white fence