Can you explain the hierarchy of subtlety and the ultimate goal of existence as described in Chapter 19?

Chapter 19 presents a philosophical hierarchy based on subtlety. It begins with the Soul (Atma), described as a Great Power. Subtler than the Soul is the Unmanifest (Avyakta), also referred to as Space or Maya. Subtler than all of these is the Purusha, or the Supreme Being. This Purusha is identified as the ultimate goal where the senses and the mind finally find rest. Chapter 19 explicitly states that this ultimate destination, the pinnacle of this subtle hierarchy, is indeed the Pure Brahman. Attaining this state of liberation and union with the Supreme Self is presented as the fulfillment of the soul and the duty of human birth.