This Chapter from a Taoist alchemical treatise, detailing the cyclical interplay of Yin and Yang within the cosmos and the human body. It describes a system of cosmology where these forces interact across vast distances, mirroring internal physiological processes. The text provides detailed instructions for cultivating internal energy by aligning personal breath and essence with these cosmic rhythms, aiming for longevity and spiritual advancement. The method involves manipulating breath (Qi) and essence (Jing) to harmonize internal energies with the external cosmic dance of Yin and Yang.