十五难曰∶经言春脉弦，夏脉钩，秋脉毛，冬脉石，是王脉耶，将病脉也？然∶弦、钩、毛、石者。
四时之脉也。春脉弦者，肝，东方木也，万物始生，未有枝叶，故其脉之来，濡弱而长，故曰弦。夏脉
钩者，心，南方火也，万物之所茂，垂枝布叶，皆下曲如钩，故其脉之来疾去迟，故曰钩。秋脉毛者，肺
，西方金也，万物之所终，草木华叶，皆秋而落，其枝独在，若毫毛也，故其脉之来，轻虚以浮，故曰毛
。冬脉石者，肾，北方水也，万物之所藏也，盛冬之时，水凝如石，故其脉之来，沉濡而滑，故曰石。此
四时之脉也。如有变奈何？
然∶春脉弦，反者为病。何谓反？然∶其气来实强，是谓太过，病在外；气来虚微，是谓不及，
病在内。气来厌厌聂聂，如循榆叶曰平；益实而滑，如循长竿曰病；急而劲益强，如新张弓弦曰死。
春脉微弦曰平，弦多胃气少曰病，但弦无胃气曰死，春以胃气为本。
夏脉钩，反者为病。何谓反？然∶其气来实强，是谓太过，病在外；气来虚微，是谓不及，病在
内。其脉来累累如环，如循琅 曰平？来而益数，如鸡举足者曰病；前曲后居，如操带钩曰死。夏脉
微钩曰平，钩多胃气少曰病，但钩无胃气曰死，夏以胃气为本。
秋脉毛，反者为病。何谓反？然；其气来实强，是谓太过，病在外；气来虚微，是谓不及，病在
内。其脉来蔼蔼如车盖，按之益大曰平；不上不下，如循鸡羽曰病；按之萧索，如风吹毛曰死。秋脉微毛
曰平，毛多胃气少曰病，但毛无胃气曰死，秋以胃气为本。
冬脉石，反者为病。何谓反？然∶其气来实强，是谓太过，病在外；气来虚微，是谓不及，病在内
。脉来上大下兑，濡滑如雀之啄曰平∶啄啄连属，其中微曲曰病；来如解索，去如弹石曰死。冬脉微石
曰平，石多胃气少曰病，但石无胃气曰死，冬以胃气为本。
胃者，水谷之海，主禀，四时皆以胃气为本。是谓四时之变病，死生之要会也。
脾者，中州也，其平和不可得见，衰乃见耳。来如雀之啄，如水之下漏，是脾衰见也。
第十五难说：医经上讲，春季的脉象呈弦状，夏季的脉象呈钩状，秋季的脉象呈毛状，冬季的脉象呈石状，这些是当令的旺脉呢，还是病脉呢？回答说：弦、钩、毛、石这四种脉象，是顺应四季变化的正常脉象。
春季脉象呈弦状，是因为肝属东方木，万物开始生长，尚未长出枝叶，所以它的脉气来势，柔和虚弱而长，因此称为弦。
夏季脉象呈钩状，是因为心属南方火，万物茂盛，枝条下垂，叶片舒展，都像弯曲的钩子一样，所以它的脉气来势急去势缓，因此称为钩。
秋季脉象呈毛状，是因为肺属西方金，万物成熟终结，草木的花叶都在秋天凋落，只剩下枝干独自存在，像毫毛一样，所以它的脉气来势，轻浮虚软，因此称为毛。
冬季脉象呈石状，是因为肾属北方水，万物潜藏，在严冬时节，水凝结得像石头一样坚硬，所以它的脉气来势，沉取濡滑，因此称为石。这就是顺应四时的正常脉象。如果发生变异该怎么办呢？
回答说：春季脉象本应弦，如果不弦反而出现其他情况就是病。什么叫反常呢？回答说：如果脉气来势坚实强劲，这叫“太过”，病在体表；如果脉气来势虚弱细微，这叫“不及”，病在体内。
（正常的春脉）脉气来势从容和缓，如抚摸榆叶般柔和，这是平脉；如果脉气更加实滑，如抚摸长竿般僵硬，这是病脉；如果脉气紧急劲强，如同刚拉开的弓弦那样紧绷，这是死脉。
春季脉象微带弦意且有胃气为平脉，弦意多而胃气少为病脉，只有弦意而没有胃气为死脉，春季脉象以胃气为本。
夏季脉象本应钩，如果不钩反而出现其他情况就是病。什么叫反常呢？回答说：如果脉气来势坚实强劲，这叫“太过”，病在体表；如果脉气来势虚弱细微，这叫“不及”，病在体内。
（正常的夏脉）脉气来势连续圆润，如抚摸美玉般光滑，这是平脉；如果脉气来势更数且急促，如鸡抬脚般轻快杂乱，这是病脉；如果脉气前段弯曲后段僵直，如拿着衣带上的钩子般生硬，这是死脉。
夏季脉象微带钩意且有胃气为平脉，钩意多而胃气少为病脉，只有钩意而没有胃气为死脉，夏季脉象以胃气为本。
秋季脉象本应毛，如果不毛反而出现其他情况就是病。什么叫反常呢？回答说：如果脉气来势坚实强劲，这叫“太过”，病在体表；如果脉气来势虚弱细微，这叫“不及”，病在体内。
（正常的秋脉）脉气来势盛大如车盖，按之感觉更大，这是平脉；如果脉气不上不下，如抚摸鸡羽般轻涩，这是病脉；如果按之萧索无力，如风吹羽毛般散乱，这是死脉。
秋季脉象微带毛意且有胃气为平脉，毛意多而胃气少为病脉，只有毛意而没有胃气为死脉，秋季脉象以胃气为本。
冬季脉象本应石，如果不石反而出现其他情况就是病。什么叫反常呢？回答说：如果脉气来势坚实强劲，这叫“太过”，病在体表；如果脉气来势虚弱细微，这叫“不及”，病在体内。
（正常的冬脉）脉气来势上部大下部小，濡滑如麻雀啄食般节奏均匀，这是平脉；如果脉气连连相连但中间略有曲折，这是病脉；如果脉气来时如解开的绳索般散乱，去时如弹石般坚硬，这是死脉。
冬季脉象微带石意且有胃气为平脉，石意多而胃气少为病脉，只有石意而没有胃气为死脉，冬季脉象以胃气为本。
胃是受纳水谷的海，主司营养供给，四季的脉象都以胃气为本。这就是四季变病的规律，也是判断生死的关键所在。
脾位于中焦，其平和的状态通常不可见，只有在衰败时才会显现。如果脉气来势如麻雀啄食般断续，或如水漏下般点滴不继，这就是脾脏衰败的表现。
Difficulty 15 states: The classic texts mention that the spring pulse is *xian* (string-like), the summer pulse is *gou* (hook-like), the autumn pulse is *mao* (feather-like), and the winter pulse is *shi* (stone-like). Are these the pulses of the thriving seasons (*Wang Mai*, pulses corresponding to the dominant season) or are they pathological pulses? The answer is: *Xian*, *gou*, *mao*, and *shi* are the pulses of the four seasons.
The spring pulse is *xian* because the Liver corresponds to Wood in the East. When all things begin to sprout, there are no branches or leaves yet; thus, the arrival of its pulse is soft, weak, and long, hence it is called *xian*.
The summer pulse is *gou* because the Heart corresponds to Fire in the South. All things flourish at this time; the hanging branches and spreading leaves curve downwards like hooks. Thus, the arrival of its pulse is rapid, and its departure is slow, hence it is called *gou*.
The autumn pulse is *mao* because the Lungs correspond to Metal in the West. All things reach their conclusion at this time; the flowers and leaves of grass and trees fall in autumn, leaving only the branches exposed, resembling fine hairs. Thus, the arrival of its pulse is light, empty, and floating, hence it is called *mao*.
The winter pulse is *shi* because the Kidneys correspond to Water in the North. All things are stored at this time. In deep winter, water freezes as hard as stone. Thus, the arrival of its pulse is deep, soft, and slippery, hence it is called *shi*. These are the pulses of the four seasons. What happens if there are variations?
The answer is: The spring pulse should be *xian*; deviation from this indicates disease. What constitutes a deviation? The answer is: If the Qi arrives solid and strong, it is termed "Excess" (*Tai Guo*), indicating disease in the exterior; if the Qi arrives deficient and faint, it is termed "Deficiency" (*Bu Ji*), indicating disease in the interior.
A normal pulse arrives gently and softly, like feeling elm leaves. A pulse that becomes more solid and slippery, like feeling a long bamboo pole, indicates disease. A pulse that is urgent, forceful, and increasingly rigid, like a newly strung bowstring, indicates death.
A spring pulse that is slightly *xian* indicates health; one that is predominantly *xian* with little Stomach Qi indicates disease; one that is purely *xian* without Stomach Qi indicates death. The spring pulse takes Stomach Qi as its foundation.
The summer pulse should be *gou*; deviation from this indicates disease. What constitutes a deviation? The answer is: If the Qi arrives solid and strong, it is termed "Excess," indicating disease in the exterior; if the Qi arrives deficient and faint, it is termed "Deficiency," indicating disease in the interior.
A normal pulse arrives continuously and roundly, like feeling polished jade. A pulse that becomes more frequent and hurried, like a chicken lifting its feet, indicates disease. A pulse that curves forward and stays rigid backward, like handling a belt hook, indicates death.
A summer pulse that is slightly *gou* indicates health; one that is predominantly *gou* with little Stomach Qi indicates disease; one that is purely *gou* without Stomach Qi indicates death. The summer pulse takes Stomach Qi as its foundation.
The autumn pulse should be *mao*; deviation from this indicates disease. What constitutes a deviation? The answer is: If the Qi arrives solid and strong, it is termed "Excess," indicating disease in the exterior; if the Qi arrives deficient and faint, it is termed "Deficiency," indicating disease in the interior.
A normal pulse arrives grandly like a chariot canopy, becoming larger upon pressure. A pulse that neither rises nor falls, like feeling a chicken feather, indicates disease. A pulse that feels desolate upon pressure, like wind blowing through feathers, indicates death.
An autumn pulse that is slightly *mao* indicates health; one that is predominantly *mao* with little Stomach Qi indicates disease; one that is purely *mao* without Stomach Qi indicates death. The autumn pulse takes Stomach Qi as its foundation.
The winter pulse should be *shi*; deviation from this indicates disease. What constitutes a deviation? The answer is: If the Qi arrives solid and strong, it is termed "Excess," indicating disease in the exterior; if the Qi arrives deficient and faint, it is termed "Deficiency," indicating disease in the interior.
A normal pulse is large above and small below, soft and slippery like a sparrow pecking. A pulse that pecks continuously but has slight irregularities in between indicates disease. A pulse that arrives like an untying rope and departs like a striking stone indicates death.
A winter pulse that is slightly *shi* indicates health; one that is predominantly *shi* with little Stomach Qi indicates disease; one that is purely *shi* without Stomach Qi indicates death. The winter pulse takes Stomach Qi as its foundation.
The Stomach is the sea of water and grain, governing nourishment. The pulses of all four seasons take Stomach Qi as their foundation. This is the key principle for understanding seasonal variations in disease and determining life and death.
The Spleen resides in the central region. Its healthy state is imperceptible; it is only seen when declining. If the pulse arrives like a sparrow pecking or like water dripping from a leak, this manifests as Spleen decline.