What does Chapter 4 say about the mission and work of saints once they descend to the world of mortals?

According to Chapter 4 of the Sai Satcharitra, the mission of saints is multifaceted and selfless. Their primary work is to protect the system of castes and stages of life and to destroy irreligion. They specifically protect the humble, poor, and weak. The text poetically describes their mission as filling the 'foundation of Renunciation' to build the 'temple of Ultimate Truth.' By working within the framework of worldly activity, they uplift devotees, awaken faith, and restore religion. This chapter clarifies that once their specific work is fulfilled, their incarnation comes to an end.