What is Grand Macrocosmic Orbit 大周天

  The Grand Macrocosmic Orbit is the second stage of the internal alchemy techniques in Taoist Neidan school, namely the process of refining qi to transform into spirit.

It is carried out on the basis of the Microcosmic Orbit stage. Internal alchemy theory holds that through the Grand Macrocosmic Orbit, spirit and qi are closely combined and embrace each other inseparably to achieve the purpose of prolonging life. It is called "great" because its internal qi circulates not only along the Ren (Conception) and Du (Governor) vessels but also through other meridians. Relatively speaking, its scope is larger than that of the Small Heavenly Circuit, hence the name "Great Heavenly Circuit".

   According to internal alchemy theory, after the Small Heavenly Circuit stage, the acquired essence-qi is enriched and gradually returned to the congenital essence-qi, so the Great Heavenly Circuit is guided by the Diagram of Innate Eight Trigrams. On the Innate Eight Trigrams diagram, the north-south positions correspond to Qian (Heaven) and Kun (Earth) trigrams, but in practice, internal alchemy always focuses on Kan (Water) and Li (Fire) trigrams, which are located at the Mao (east, 5-7 a.m.) and You (west, 5-7 p.m.) positions. Therefore, the Great Heavenly Circuit is also called "Heaven-Earth Union" or "Mao-You Heavenly Circuit".