This is a chapter from Lü Dongbin's Secret of the Golden Flower, focusing on the concept of Zhou Tian, or the Heavenly Cycle, a Taoist internal alchemy practice. It emphasizes cultivating inner stillness and naturalness rather than forceful manipulation of qi, likening the heart to the North Star and qi to orbiting stars. The practice aims to refine the cognitive spirit and generate innate true qi ("xian tian zhen qi"), achieving a harmonious balance of yin and yang. The text also discusses the relationship between the "true midnight hour" and the "living midnight hour," illustrating the importance of clear perception in spiritual practice.