When the light is made to move in a circle, all the energies of heaven and earth, of the light and the dark, are crystallized. That is what is termed seed-like thinking, or purification of the energy
This passage defines ‘circulation of the light’ as the foundational alchemical-meditative practice through which opposed cosmic energies are unified and crystallized into spirit.
, The Secret of the Golden Flower: A Chinese Book of Life, 1931thesis