Can you explain the philosophical concept of duality and non-duality as presented in Chapter 14?

In Chapter 14, the text delves into the philosophical teachings of oneness versus duality. It states that the intellect which establishes duality, or sees differences, is pure ignorance that leads to the cycle of birth and death. In contrast, the chapter teaches that the same Essence in one's own body is present throughout the entire universe. True wisdom comes from turning away from ignorance and surrendering to this Essence, which brings about the realization of oneness. As explained in the text, achieving a state of non-duality is impossible if even a trace of difference remains in the mind, as Brahman pervades everything from Brahma down to a blade of grass.