How does this passage explain the relationship between the Guru, Brahman, and the transient world as a means for spiritual attainment?

Chapter 45 presents a profound philosophical framework for spiritual attainment. It posits that Brahman is eternal while the world is transient, and crucially, it identifies the Guru alone as the true Brahman—a "solid mass of Brahman-consciousness." The prescribed path, or means, involves a constant feeling cultivated by renouncing the transient world and meditating only on the Guru. This act of renunciation gives birth to dispassion (Vairagya). By focusing on the Sadguru as the embodiment of Brahman, a seeker eventually develops a state where divinity arises in all beings, which the text calls "undifferentiated worship" (Abheda-bhajan), completing the spiritual journey.