《黄帝内经·灵枢·血络论》
黄帝说：有时针刺血络放血会使病人昏倒其原因是什么？
黄帝曰：刺血络而仆者，何也？
The Yellow Emperor said: Sometimes, after acupuncture has pricked the blood vessels and let blood, the patient will faint. What is the reason for this?