How does Chapter 19 illustrate the concept that the Soul remains pure and untainted, despite its presence in the material world?

Chapter 19 uses several metaphors to explain how the Soul remains untainted by the world of Maya. The primary analogy is that of a crystal, which may appear red, black, or yellow depending on the color of an object placed near it, yet the crystal itself remains pure, colorless, and distinct. The chapter also describes false perceptions that obscure reality, such as seeing a mirage on a plain, the glitter of silver on a seashell, or mistaking a coiled rope for a snake. In the same way that superimposing a snake on a rope is false, Chapter 19 states that the ego-driven belief of "I am the body" is a false bondage, as the Soul is inherently self-luminous, pure consciousness, and changeless.