脉经曰脉来 者为虚 缓者为虚 微则为虚 弱为虚 濡为虚 弦为中虚 脉来细而微
者血气俱虚 脉小者血气俱少
内经曰脉虚气虚尺虚是谓重虚所谓气虚者言无常也尺虚者行步 然脉虚者不象阴也如此
者滑则生涩则死
要略曰脉芤为虚 脉沉小迟者脱气
难经曰至脉从下上损脉从上下也一损损于皮毛皮聚而毛落二损损于血脉血脉虚少不能荣
于五
脏六腑三损损于肌肉肌肉消瘦饮食不能为肌肤四损损于筋筋缓不能自收持五损损于骨骨痿不
能
起于床反此者至脉之病也从上下者骨痿不能起于床者死从下上者皮聚而毛落者死然治损之法
损其肺者益其气损其心者调其荣卫损其脾者调其饮食适其寒温损其肝者缓其中损其肾者益其
精
病机机要论曰虚损之疾寒热因虚而感也感寒则损阳阳虚则阴盛自上而下治之宜以辛甘淡
过于
胃则不可治也感热则损阴阴虚则阳盛故损自下而上治之宜以苦酸咸过于脾则不可治也自上而
损者一损损于肺皮聚而毛落二损损于心血脉虚少不能荣于脏腑妇人月水不通三损损于胃饮食
不为肌肤自下而损者一损损于肾骨痿不能起于床二损损于肝筋缓不能自收持三损损于脾饮食
不
能消克论曰心肺损而色蔽肾肺损而形痿谷不能化而脾损感此病者皆损之病也渐渍之深皆虚劳
之疾也
谨按难经论损脉证者谓因劳损其形体血脉脏腑内外因也故治法宜调养之以上论者谓因虚
外感
也然伤寒中暑初感必先足太阳今归之于手太阴足少阴者盖肺主皮毛肾主骨尔若此则因虚外感
不独伤于足经也但足经伤寒有传变恐不可作损证论乎
《脉经》说：脉象来势无力称为虚，缓弱称为虚，微细称为虚，软弱称为虚，濡软称为虚，弦紧属于中气虚弱，脉象细而微是血气和气都虚弱，脉象小是血和气都少。
《内经》说：脉虚、气虚、尺部（手腕内侧近腕横纹处）脉虚，这叫做“重虚”。所谓气虚，表现为言语无序；尺部脉虚，表现为行走不稳；脉虚则不能反映阴血的充盈状态。像这样，脉滑利者生，脉涩滞者死。
《金匮要略》说：脉芤（浮大中空，如按葱管）为虚，脉沉小迟者为脱气。
《难经》说：至脉是从下往上损，损脉是从上往下损。一损损伤在皮毛，皮肤聚拢而毛发脱落；二损损伤在血脉，血脉虚少，不能滋养五脏六腑；三损损伤在肌肉，肌肉消瘦，饮食不能转化为肌肤营养；四损损伤在筋，筋脉弛缓，不能自主收持；五损损伤在骨，骨痿软弱，不能起床。与此相反的是至脉的病变，从下往上发展，骨痿不能起床的死亡；从上往下发展，皮肤聚拢而毛发脱落的死亡。然而治疗损证的方法：损伤肺的，补益其气；损伤心的，调和营卫；损伤脾的，调节饮食，适应寒温；损伤肝的，舒缓其中气；损伤肾的，补益其精。
《病机机要论》说：虚损的疾病，是因为正气虚弱而感受外邪引起的。感受寒邪则损伤阳气，阳虚则阴盛，这种损伤自上而下发展，治疗适宜用辛、甘、淡味药，如果损伤超过胃腑，就不可治了。感受热邪则损伤阴液，阴虚则阳盛，这种损伤自下而上发展，治疗适宜用苦、酸、咸味药，如果损伤超过脾脏，就不可治了。自上而下发展的损证：一损损伤在肺，皮肤聚拢而毛发脱落；二损损伤在心，血脉虚少，不能滋养脏腑，妇女月经不通；三损损伤在胃，饮食不能转化为肌肤营养。自下而上发展的损证：一损损伤在肾，骨痿不能起床；二损损伤在肝，筋脉弛缓不能自主收持；三损损伤在脾，饮食不能消化运化。论述说：心肺受损则面色晦暗，肾肺受损则形体痿弱，水谷不能运化则是脾受损。感受这些病症的，都是损证。逐渐浸淫深入，都是虚劳类的疾病。
谨按：《难经》论述损证的脉象和症状，是指因为劳倦损伤了形体、血脉、脏腑，涉及内外因素，所以治疗方法适宜调养。以上论述是指因为体虚而感受外邪。然而伤寒和中暑初起感受时，必定先侵犯足太阳膀胱经。现在将其归属于手太阴肺经和足少阴肾经，大概是因为肺主皮毛，肾主骨的缘故。如果是这样，那么因虚而感外邪，并不只伤害足经。只是足经伤寒有传变过程，恐怕不能当作损证来论述呢？
The *Mai Jing* (Pulse Classic) states: A pulse that comes with a weak force is termed Xu (Deficiency); a slow and weak pulse is Xu; a fine and faint pulse is Xu; a soft and weak pulse is Xu; a soggy pulse is Xu; a wiry pulse indicates Middle Qi Deficiency (deficiency of the Spleen and Stomach Qi); a pulse that is fine and faint indicates both Blood and Qi are deficient; a small pulse indicates both Blood and Qi are scant.
The *Nei Jing* (Inner Canon) states: Pulse deficiency, Qi deficiency, and Chi (Cun-Kuan distance near the wrist crease) pulse deficiency constitute "Chong Xu" (Double Deficiency). What is meant by Qi deficiency is disordered speech; what is meant by Chi pulse deficiency is unsteady gait; pulse deficiency fails to reflect the fullness of Yin blood. In such cases, a slippery pulse indicates survival, while a choppy pulse indicates death.
The *Jin Gui Yao Lue* (Essential Prescriptions of the Golden Cabinet) states: A Kou (Hollow) pulse indicates Deficiency; a deep, small, and slow pulse indicates Loss of Qi.
The *Nan Jing* (Classic of Difficult Issues) states: Zhi pulses (increasing in frequency from bottom to top) involve damage progressing upwards; Sun pulses (decreasing in frequency from top to bottom) involve damage progressing downwards. First-degree damage affects the skin and hair: the skin gathers and hair falls out. Second-degree damage affects the blood vessels: the vessels become deficient and scarce, failing to nourish the Five Zang and Six Fu organs. Third-degree damage affects the muscles: the muscles emaciate, and food intake fails to transform into muscle tissue. Fourth-degree damage affects the sinews: the sinews become flaccid, unable to hold or control themselves. Fifth-degree damage affects the bones: bone atrophy occurs, making it impossible to rise from bed. The reverse applies to Zhi disease progression. Damage progressing upwards leads to death if bone atrophy prevents rising from bed; damage progressing downwards leads to death if skin gathering and hair loss occur. However, the method for treating Sun diseases is as follows: For lung damage, benefit its Qi; for heart damage, regulate Ying and Wei (Nutritive and Defensive Qi); for spleen damage, regulate diet and adapt to cold and warmth; for liver damage, soothe its interior; for kidney damage, benefit its Essence.
The *Bing Ji Yao Yao Lun* (Treatise on Pathogenesis Essentials) states: Diseases of deficiency and wasting arise because external pathogens are contracted due to internal deficiency. Contracting cold damages Yang; Yang deficiency leads to Yin excess. This damage progresses from top to bottom, and treatment should employ Pungent, Sweet, and Bland flavors. If the damage exceeds the Stomach, it becomes incurable. Contracting heat damages Yin; Yin deficiency leads to Yang excess. This damage progresses from bottom to top, and treatment should employ Bitter, Sour, and Salty flavors. If the damage exceeds the Spleen, it becomes incurable. Damage progressing from top to bottom: First-degree damage affects the Lung, causing skin gathering and hair loss; second-degree damage affects the Heart, causing blood vessels to be deficient and unable to nourish the organs, resulting in amenorrhea in women; third-degree damage affects the Stomach, where food intake fails to nourish the flesh. Damage progressing from bottom to top: First-degree damage affects the Kidney, causing bone atrophy and inability to rise from bed; second-degree damage affects the Liver, causing flaccid sinews and inability to control movement; third-degree damage affects the Spleen, where food cannot be digested and transformed. The commentary states: When the Heart and Lung are damaged, the complexion becomes dull; when the Kidney and Lung are damaged, the form becomes atrophic; when grain and water fail to transform, the Spleen is damaged. Those contracting these illnesses suffer from Sun diseases. As these conditions gradually penetrate deeply, they all become Xu Lao (Deficiency and Emaciation) diseases.
Respectfully noted: The *Nan Jing* discusses the pulse and symptoms of Sun diseases, referring to physical, vascular, and organ damage caused by overwork, involving both internal and external factors; thus, the treatment method is suitable for nourishing and regulating. The above discussions refer to external pathogenic contraction due to internal deficiency. However, initial contraction of Shang Han (Cold Damage) and Zhong Shu (Heat Stroke) must first invade the Foot Taiyang Bladder Channel. Now, attributing this to the Hand Taiyin Lung Channel and Foot Shaoyin Kidney Channel is likely because the Lung governs the skin and hair, and the Kidney governs the bones. If so, then external contraction due to deficiency does not solely injure the Foot Channels. However, since Foot Channel Shang Han involves transmission and transformation, perhaps it should not be discussed as a Sun disease?