What analogy does Chapter 47 use to describe the purifying power of saints?

In its opening verses, Chapter 47 uses a powerful analogy involving the sacred River Bhagirathi, or the Ganges, to demonstrate the immense purifying power of saints. The text explains that while the river washes the feet of the world, it becomes soiled with impurities. In order to cleanse herself of these accumulated sins, the river herself desires the dust from the feet of saints. The chapter personifies the Ganges, having her wonder, "When will the feet of saints touch me? When will they come to bathe within me?" This illustrates that the spiritual purity of saints is so great that even a holy entity like the Ganges seeks them for deliverance.