What are the main reasons given in Chapter 4 for why saints descend to the world of mortals?

Chapter 4 of the Sai Satcharitra provides several main reasons for the advent of saints. They incarnate when religion is in decay, people lose their way, and society is in turmoil. This includes when people prioritize worldly gains like wealth and family over the ultimate spiritual goal (Paramartha). Saints descend to awaken religion, protect the system of castes and stages of life, and to destroy irreligion. A key reason highlighted is to protect the humble, poor, and weak, and to uplift the distressed. The chapter makes it clear that this mission is entirely selfless, as saints are already liberated and take form purely for the sake of others, with no self-interest.