What is the root cause for a soul being trapped in the cycle of worldly existence (Samsara)?

The core reason a soul is trapped in the cycle of birth and death, or Samsara, is the perception of difference and duality. As explained in Chapter 37, the belief that 'Parabrahman is different from me; I am not that, I am something else' is what subjects a person to death. This feeling of being separate from the ultimate reality is a form of ignorance that perpetuates the cycle where 'Death follows birth, and rebirth follows death'. The text emphasizes that this cycle of worldly existence turns eternally behind one who holds such knowledge of difference, deluded by ignorance.