“The term waidan conventionally denotes a broad and diverse range of doctrines and practices focused on the compounding of elixirs whose ingredients are minerals, metals, and—less frequently—plants. This designation is often contrasted to neidan or “inner alchemy,” but the two terms originated within the context of neidan itself, where they initially referred to facets or stages of the inner alchemical process (Robinet 1991).”
“Waidan has a history of about fifteen centuries, from its origin in the Han period (202BCE-220CE) to its culmination in the Tang (618-907), followed by its decline in the Song (960-1279) and Yuan (1260-1368) and its virtual disappearance in Ming times (1368-1644).” — Fabrizio Pregadio, Encyclopedia of Taoism, Routledge, 2008.
“Every time I try to investigate waidan teachings for myself I fail. Speaking shortly, people practicing waidan should have quite a nerve or at least should be born extraverts. For us, introverts, neidan is good enough to feel happiness in everything inside and outside, that’s a trick.” — Sri Yantra Master, today, 30 October 2014 🙂