What is the ultimate nature of the Soul and its final goal according to Chapter 19?

Chapter 19 describes the Soul (Atma) as a Great Power that is changeless, imperishable, self-luminous, pure consciousness, and formless. It is fundamentally distinct from the body, senses, mind, and life-force. The text further details a hierarchy of subtlety, stating that even more subtle than the Soul is the Unmanifest (Avyakta or Maya), and subtler still is the Purusha (the Supreme Being). The ultimate goal, or the final resting place for the senses and mind, is to reach this Purusha, which is equated with the Pure Brahman. This attainment is the fulfillment of the soul's purpose, leading to eternity, fearlessness, and liberation.