Rasayana is one of the eight original branches of classical Ayurveda (Ashtanga Ayurveda). The Charaka Samhita, one of Ayurveda's foundational texts devotes the opening chapters of its Chikitsa Sthana (treatment section) entirely to it, describing specific formulations and regimens for tissue renewal rather than general wellness advice.

The underlying idea is mechanical, not mystical: when digestion (agni) is weak or irregular, nutrients fail to convert fully into tissue (dhatu), leaving someone fed but undernourished at a cellular level.

Rejuvenation Therapy first uses steam and oil therapy to clear this internal congestion, then delivers concentrated herbal nutrition transdermally through the skin, via prolonged contact with warm medicated oils bypassing a digestive system that may not be absorbing well on its own. That's why the program runs over consecutive days rather than as a single session: tissue renewal happens in layers, over time, not in one sitting.