(Kāya Kalpa): “Ageless body” or “body fashioning,” is an Ayurvedic treatment for rejuvenating the body. It calls for seclusion in darkness, meditation, and the application of various herbal concoctions. It is even seen as a form of yoga—Ayurvedic medicine was developed in Southern India at about the same time that Hatha Yoga was being developed. Kaya kalpa has three main objectives: Slowing the aging process, maintaining excellent physical health and youthful vitality, and delaying physical death until the attainment of jivanmukta (spiritual liberation while in a physical body). In Hridaya Yoga, spending a period of time meditating in total darkness is referred to as a Dark Retreat. This practice is equivalent to kaya kalpa, however, its main objective is not physical rejuvenation but the direct understanding that we are not just the physical body.