Can you explain the metaphor at the beginning of the chapter about the river that wants to be purified?

Chapter 47 opens with a powerful metaphor of a river that, despite washing away the sins of others, feels it has accumulated impurities itself. To achieve its own purification, the river deeply desires contact with the holiest of things: the dust from the feet of saints. The text personifies the river, which yearns and asks, "When will the feet of saints touch me?" This imagery serves to illustrate a core message: even things we perceive as inherently pure can be elevated and truly sanctified by the presence of a great saint. This sets the stage for the purifying power of Sai Baba's stories that follow.