If it is time, a Sunday is 24 hours. The size of Sunday generally refers to Neidan, small Sunday is also called meridian Sunday, and big Sunday is also called You Mao Sunday. On the basis of Xiao Zhoutian, Zhou Zhoutian further cultivated the eight strange meridians, and the twelve meridians fully blended them, so that God and Qi were closely combined, and God followed them, reaching the whole body, being broad-minded and healthy.