How does this chapter describe the concept of non-duality and a devotee merging with Sai?

Chapter 52 uses several powerful metaphors to explain the state of non-duality achieved by a devotee. It compares the process to a river entering the ocean, where it forgets its 'river-ness' and becomes one with the ocean. Similarly, when a devotee takes refuge at Sai's feet, the sense of duality vanishes. Other analogies mentioned include two lamps embracing to become one light, salt instantly becoming one with the ocean, and the inseparability of scent from camphor. The key to this union, as the chapter describes, is for the devotee to relinquish their 'I-ness,' which allows them to become equal with Him.