Ling Shu (Spiritual Axle), a 2,700 old medical text, considers some important points in acupuncture

“Before the qi arrives, it feels light, slippery, and slack, like one is resting in a deep corner of an empty hall. When the qi arrives, the feeling is sinking, rough, and tight, as though a fish has swallowed the bait and is darting up and down in the water.”