How do the concepts of duality and non-duality relate to the fear of death in Sai's teachings?

According to the teachings in Chapter 37, duality is the root of fear. Where there is an obsession with duality, the perception of manifoldness, fear enters. This perception is established by ignorance (Avidya). To overcome the great fear of death, one must serve the non-distinguished state, where there is no trace of fear. This is achieved by acquiring the science of the oneness of Brahman and the Self through the Guru, which removes ignorance and the knowledge of manifoldness, thereby ending the cycle of birth and death.