What does Chapter 37 say is the root cause of being trapped in the cycle of birth and death (Samsara)?

The primary cause for being trapped in the eternal cycle of worldly existence, or Samsara, is the mistaken belief in one's separation from the ultimate reality. Chapter 37 clarifies that a person who holds the knowledge of difference—thinking, "Parabrahman is different from me; I am not that"—is always subject to death. This delusion, born of ignorance, ensures that death follows birth and rebirth follows death, causing the cycle of Samsara to turn eternally behind that individual.