According to the teachings, what is the root cause of sorrow and how can one escape the cycle of rebirth?

The primary cause of sorrow is the firm 'body-consciousness,' the mistaken belief that "Body is me, this is my wealth." Chapter 37 identifies this as the knot in the heart and the source of Maya's sorrow. This attachment leads to desires, which are described as the seeds of action that perpetuate the cycle of rebirth. To escape this cycle, one must destroy these desires at their very root. The text states that when desires are destroyed, the knot in the heart is removed, and a mortal person can become immortal, which is the core teaching of the Vedanta.