Can you explain the metaphor of the Ganges River used at the beginning of Chapter 47?

In Chapter 47, a powerful metaphor is used to illustrate the supreme purity of saints like Sai. The text describes the River Bhagirathi (Ganges) as a purifier that washes the feet of the world but, in doing so, becomes soiled herself with accumulated impurities. To cleanse herself of these sins, the sacred river longs for the dust from the feet of saints. The chapter poetically asks, "When will the feet of saints touch me?" This metaphor powerfully conveys that the holiness of a true saint is so great that even a revered entity like the Ganges seeks their presence for its own purification.