《黄帝内经·灵枢·决气》
岐伯说：位于中焦的脾胃接纳饮食物，吸收其中的精微物质，经过气化变成红色的液体，这就叫做血。
岐伯曰：中焦受气，取汁变化而赤，是谓血。
Qibo said: “The spleen and stomach in the middle Jiao receive food and drink, absorb its essential substances, and turn them into red liquid through vaporization. That is called blood.”