What is the 'knot in the heart' mentioned in the teachings, and how is it related to sorrow and the Self?

In Chapter 37, the concept of the 'knot in the heart' is identified as the source of sorrow. This knot is defined as firm 'body-consciousness,' which is the deep-seated belief that 'Body is me, this is my wealth.' This identification with the physical body and its possessions is described as the dwelling place of Maya's sorrow. The text suggests that when all such bondage ceases and is destroyed, the Self manifests effortlessly. This is compared to the sun, which shines by its own light once the clouds that were obscuring it have moved away, indicating that liberation from this knot reveals our true nature.