Bhagavad Gita Chapter 9, The Royal Knowledge and the Royal Secret (Rāja Vidyā Rāja Guhya Yoga), holds deep significance in Advaita Vedanta, as it emphasizes the ultimate truth that everything is Brahman and that the apparent duality of the world is an illusion (Maya). Krishna declares that He is both the cause and the substratum of all existence, yet untouched by the changing universe. This aligns with Advaita’s core teaching that Brahman is the only reality, and the perceived world is a transient manifestation within It. The realization of this truth leads to liberation (Moksha), where the individual self (Jiva) recognizes its non-difference from the Supreme (Paramatma).

Krishna explains that while all beings exist in Him, He remains unattached and unaffected by their existence, much like space holding all objects but remaining unchanged. This analogy resonates with Advaita's teaching that the world appears due to ignorance (Avidya), but upon true knowledge (Jnana), one realizes that the Self alone is real. The dualistic perception of God as separate from oneself is due to ignorance, and devotion (Bhakti) with the right understanding becomes a means to transcend this illusion. Those who worship Krishna with unwavering faith are purified and gradually recognize their identity with Him, moving beyond the cycle of birth and death.

The chapter also clarifies that all actions and beings are ultimately governed by the Supreme Consciousness, yet Krishna remains detached, much like the Advaitic idea that Brahman is the ultimate witness (Sakshi) and not an active doer. He proclaims that even those of lower birth or background, when surrendering to Him with pure devotion, attain the highest truth. This dissolves all notions of duality between the seeker and the sought, leading to the realization that liberation is not about reaching a distant God but about shedding the illusion of separation.

In essence, Chapter 9 is a profound exposition of the non-dual reality hidden beneath devotion and knowledge. The "royal secret" Krishna reveals is that through faith, surrender, and self-inquiry, one realizes that the individual soul was never separate from the Supreme. The path of Bhakti, when combined with Jnana, dissolves ego and ignorance, leading to the Advaitic realization—Tat Tvam Asi ("You are That"). This chapter, therefore, serves as a bridge between devotion and non-duality, showing that true surrender is the surrender of false individuality, allowing the seeker to abide in the infinite, unchanging Brahman.