Based on the text in Chapter 37, what is the underlying cause of the cycle of birth and death (Samsara), and what is its relationship to Brahman?

Chapter 37 explains that the root cause of the eternal cycle of worldly existence (Samsara) is the ignorance that creates a sense of separation from the divine. The text asserts that a single principle, Brahman, pervades all of existence, from the creator down to a blade of grass. However, when a soul is deluded by ignorance, it perceives itself as different from this ultimate reality, thinking, "Parabrahman is different from me; I am not that." As Chapter 37 states, anyone who possesses this knowledge of difference becomes subject to the cycle of death followed by rebirth. Therefore, Samsara is perpetuated by the failure to realize one's non-dual identity with the all-pervading Brahman.