Explain how Ma and Pa operate as symbolic poles in the family. Be sure to mention the "Ma principle" and the "Pa principle".

Ma Joad is a forceful individual who is determined to keep her family together at nearly any cost; however, she shows kindness to outsiders, even sparing what little the Joad family has for those even less fortunate. Although Pa Joad is the head of the Joad household, he is not a particularly commanding presence. Ma is the one that drives the family forward. Without the ability to provide for his family, he recedes into the background, taking little initiative in deciding the fate of his relatives.

Sorry, I have not heard of the "Ma principle" and the "Pa principle."