Can you explain the analogy of the River Ganges used in Chapter 47 to describe the power of saints?

Chapter 47 uses a poignant analogy involving the River Bhagirathi (Ganges) to illustrate the purifying power of saints. The text posits that while the Ganges washes away the sins of the world, she becomes soiled herself with these accumulated impurities. To achieve her own deliverance, the river yearns for the "dust from the feet of saints." She eagerly awaits the day saints will bathe in her waters, knowing that this is the only way for her to be cleansed. This metaphor powerfully conveys the idea that saints like Sai possess a purifying ability that surpasses even that of the holy river.