What is the central message of Chapter 16 regarding the path to attaining Brahma-jnana?

The central message of Chapter 16, which is subtitled "The Quest for Brahma-jnana," is that the most certain path to attaining union with Brahman is through humble and faithful service to a Sadguru. The chapter explicitly states that by serving the Guru with faith, a servant can attain "Sayujya," or union with Brahman, and that all other means will fail. It warns against relying on one's own "cleverness" and instead advocates for complete surrender to the Guru. As Chapter 16 illustrates, the Guru is the one who provides the "Unthinkable Object" (Brahman), acting as the ultimate guide who knows the disciple's pitfalls and provides the necessary remedies for spiritual progress.