《黄帝内经·灵枢·五色》
浮露而鲜明的，主在表、在腑的病变。黄色和赤色主风病，青色和黑色主痛证，白色主寒证。
故相气不微，不知是非，属意勿去，乃知新故。
If it is superficial and bright, it indicates a disease on the surface or in the bowels. Yellow and red indicate wind disease, green and black indicate pain evidence, and white indicates cold evidence.