The embryo is conceived from the concealed Qi. Qi is developed through the (regulated) breath of the embryo. When Qi is present, the body may live; when spirit (Shen) abandons the body and the shape (i.e. embryo) disperses, death will follow. Knowing (how to cultivate) the spirit and Qi makes long life possible. Firmly protect the insubstantial emptiness (i.e. Spiritual Embryo at the Real Lower Dan Tian) so as to cultivate spirit and Qi. When spirit moves, the Qi moves; where spirit stops, the Qi stops. If you wish to have a long life, spirit and Qi must harmoniously coordinate (with each other). When the Xin (heart-mind) is not infatuated by thoughts coming or going, then (spirit and Qi) will not exit and enter, and thus will always stay naturally. To practice intelligently is the true way (of success).