According to Chapter 4 of Sai Satcharitra, what are the primary reasons a saint takes an incarnation on Earth?

Chapter 4 of the Shri Sai Satcharitra explains that saints incarnate on Earth when there is a significant decay in religion and morality. They descend when people lose sight of the ultimate spiritual goal, or Paramartha, and instead consider worldly things like wealth, status, and family as the only source of happiness. As this chapter details, saints come to awaken religion, protect the humble, poor, and weak, and destroy irreligion. Their incarnation is described as being purely for the sake of others, as they are already liberated beings and act without any self-interest.