What does Chapter 4 say about the mission of saints and what happens once that mission is accomplished?

In Chapter 4 of the Shri Sai Satcharitra, the mission of saints is clearly defined as performing the work of religion and awakening faith. They descend to Earth to protect the system of castes and stages of life, to destroy irreligion, and to protect the humble and weak. The text emphasizes that their incarnation is selfless, undertaken purely for the benefit of others who are distressed and have lost their way. This chapter further explains that the saint's presence is tied to their specific work; once their mission is fulfilled and faith is re-established, they end their incarnation.