What does Chapter 19 say is the ultimate duty of human birth and how can one achieve liberation?

Chapter 19 clearly states that the fulfillment of the soul and the primary duty of human birth is the attainment of "Eternity, fearlessness, liberation, independence, and the attainment of the Supreme Self." The path to achieving this is laid out in a specific sequence. The chapter teaches that there can be no liberation without knowledge. Furthermore, this essential knowledge cannot be gained without detachment from the world. This detachment, in turn, is only sparked when the mind truly perceives the world and all its components as transient and impermanent. Therefore, realizing the world's transient nature is the first step toward knowledge and liberation.