According to the philosophy in Chapter 19, what is the root cause of human suffering, and what is the path to liberation?

Chapter 19 identifies the root cause of suffering, or the unavoidable experience of pleasure and pain, as the ego's identification with the body, intellect, and mind. This creates a false sense of being the 'doer' and 'enjoyer' of actions. The path to liberation, as outlined in the chapter, begins with perceiving the world as transient, which sparks detachment. The text states that knowledge is not attainable without this detachment, and there can be no liberation without knowledge. Therefore, the prescribed path involves cultivating detachment to gain knowledge of the true self—the self-luminous, changeless Soul—which leads to the ultimate goal of liberation and attainment of the Supreme Self.