Based on Chapter 19, how is the ultimate nature of the Soul distinguished from the physical and mental self?

Chapter 19 provides a profound description of the Soul's true nature, differentiating it from the transient aspects of existence. The Soul is characterized as changeless, imperishable, self-luminous, pure consciousness, and formless. It is explicitly stated to be distinct from the body, senses, mind, and even the life-force. The chapter explains that the Soul is the Purusha, or the Supreme Being, and represents the ultimate goal where the senses and mind finally find rest. This state is identified as the Pure Brahman. This distinction is crucial, as Chapter 19 teaches that the ego of 'I am the body' is a false bondage for one who understands this truth.