Chapter 52 uses the metaphors of a river meeting the ocean and two lamps becoming one. What spiritual concept do these metaphors illustrate?

In Chapter 52, these metaphors illustrate the principle of non-duality achieved through devotion to the Guru. The text explains that just as a river forgets its 'river-ness' upon embracing the ocean, a devotee who takes refuge in the Guru loses their individual sense of self and merges completely, leaving no sense of duality. Similarly, the chapter describes two lamps becoming one when they embrace, resulting in a single, unified light where the state of duality vanishes. Both images powerfully convey the ultimate goal of devotion: the dissolution of the ego and the experience of complete unity with the divine.