《资治通鉴·汉纪·汉纪四十五》
像熊那样攀援树木，伸手展足，象鸟那样飞翔高空，伸腿展翅，虽然可以延年益寿，却治不了伤寒重病。用口不断吐出浊气，用鼻不断吸进清气，虽然可以使身体健康，却不能连接折断的骨骼。
夫熊经鸟伸，虽延历之术，非伤寒之理；呼吸吐纳，虽度纪之道，非续骨之膏。
Climbing trees like a bear, stretching your arms and legs, or flying high in the sky like a bird, spreading your wings, may help prolong life, but cannot cure a severe cold. Exhaling the turbid breath from your mouth and inhaling fresh air through your nose may keep your body healthy, but cannot connect broken bones.