"The reality of the past, its sleep is not a dream, its worry-free, its food is unwilling, and its interest is deep. The spirit of the saints is in the heel, and the spirit of everyone is in the throat. "

Ancient monks didn't dream when they slept, didn't feel sad when they woke up, didn't ask for a strong smell when they ate, and took a deep breath. The breath of a Taoist can reach the heel from the inside; The breath of ordinary people can only reach the throat from the outside.

Ancient saints, once breathing, can reach their heels. This Taoist way of breathing is called heel sucking, which should be a concrete description of the practice of health preservation and monasticism.