According to this chapter, what is the true purpose of an avatar like Sai Baba appearing in the world, and why do they eventually 'disappear'?

Chapter 43 explains that the fundamental purpose for the rise of great souls like Sai Baba is the "welfare of people." They are said to incarnate with the "sole desire for the welfare of devotees" and appear in a manifest form due to the collective merits and devotion of their followers. Their mission is one of protection and spiritual guidance. The text clarifies that these avatars are not subject to the involuntary cycle of birth and death. Instead, they choose to merge back into their unmanifest, true form only when their specific "task is over." As Chapter 43 states, their appearance and dissolution are for the "gathering of people," a divine play for the benefit of humanity.