The dao

produces and completes the 10,000 beings. It is nothing but the exchange between the yin and yang and then the luminous radiance of the spirits ( shen ming ). In order to be alive, mankind needs the combination of yin and yang qi , the union of the essences ( jing ) of the father and mother. Two essences combine, the physical form and the spirits are then completed, uniting the qi of heaven and earth, and giving mankind.