It is a wonderful subduer, this need of love—this hunger of the heart—as peremptory as that other hunger by which Nature forces us to submit to the yoke, and change the face of the world.
This quotation, from Chapter V of Book First, introduces an important element in Maggie's character—her extreme need for love and affection. The use of the word "hunger" stresses the overwhelming power of Maggie's need. This need can sometimes seem self-centered, yet by related her need to a body's hunger, this quotation naturalizes and normalizes it. Love here is shown to be something humbling, something with power over characters ("submit to the yoke"), instead of a force that characters use. Finally, just as hunger makes humans adapt their behavior and environment ("change the face of the world" could mean planting crops), Maggie's need for love will be seen to be a formative force on her.