Can you explain the state of "oneness" that is described as being central to Sai's yogic realization?

The state of oneness is described in Chapter 4 as the pinnacle of Sai's yogic attainment. It is a state achieved by "discarding the feeling of duality." In this realization, one understands that everything in existence, both "moving and unmoving," is fundamentally Brahman by nature. The text states that when one truly realizes "I am everything" in relation to the entire world, an indescribable happiness and supreme devotion are attained. This perspective eliminates all potential for enmity or fear, because nothing is seen as separate or "other" from the Self. This was the foundation of Sai's being, as his mind was constantly colored with this form of the Self.