According to the source, what is the root cause of the cycle of birth and death, and how can one break free from it?

Chapter 37 identifies ignorance, or Avidya, as the root cause of all worldly suffering, including the cycle of birth and death. Ignorance establishes the perception of manifoldness or duality, which in turn leads to the constant worry and bonds of worldly existence. To break free, one must counter this ignorance by acquiring knowledge (Vidya) through the scriptures and, most importantly, through the guidance of a Guru. When ignorance is removed, the perception of manifoldness disappears, and the science of oneness is realized. As the text states, for such a person, birth and death cease, and they attain the place of fearlessness.