《黄帝内经·灵枢·九针论》
岐伯说：九针之 九 ，是天地间的大数，数开始于一，而终止于九。
岐伯曰：九针者，天地之大数也，始于一而终于九。
Qibo said: The 九 in the nine needles represents a large number between heaven and earth, and the number starts from one and ends at nine.