Can you explain the concepts of duality and non-duality as taught by Sai Baba in Chapter 14?

Chapter 14 delves into the advanced philosophical concepts of duality and non-duality. It posits that the intellect which establishes duality, or 'manifoldness,' is fundamentally pure ignorance and is the cause of the cycle of birth and death. The path to liberation lies in realizing oneness, or non-duality. This is achieved through the Guru's teachings which lead to the purification of the mind. As Chapter 14 explains, one must realize that the same Essence that is in one's own body is the same essence that pervades the entire universe, from 'Brahma down to a blade of grass.' Turning away from the ignorance of perceived differences is the attainment of this non-dual state, which is one's true nature.