How does Chapter 4 characterize the fundamental nature and mission of saints when they descend to Earth?

In Chapter 4, the nature of saints is characterized as being inherently liberated, yet they are always ready to uplift the distressed and poor. Their incarnation is not for personal gain but is purely for the sake of others. The chapter describes their mission as filling the foundation of Renunciation (Nivritti) to build a temple of Ultimate Truth. They use the framework of Worldly Activity (Pravritti) to easily uplift their devotees. As outlined in Chapter 4, their primary work is to perform the duties of religion, awaken faith in people, and protect the system of castes and stages of life. Once this specific mission is fulfilled, they end their incarnation.