Can you explain the philosophical teachings on duality and non-duality as presented in Chapter 14?

Chapter 14 delves into the profound philosophical concept of oneness (Advaita) versus duality (Dvaita). It teaches that the same divine Essence that resides within one's own body is present throughout the entire universe. True wisdom lies in recognizing this uninterrupted oneness. The chapter states that surrendering to this Essence leads to liberation, whereas holding onto manifoldness, or duality, results in the endless cycle of birth and death. The intellect that establishes duality is labeled as "pure ignorance." According to the teachings in Chapter 14, it is through the Guru's guidance that the mind is purified, leading to the realization of one's true, non-dual nature. Ultimately, it posits that everything, "from Brahma down to a blade of grass," is pervaded by Brahman.