古以毛为轻之譬。《诗》大雅德 如毛， 轻也；《孟子》以一羽对百钧，又曰金重于
羽；
《汉书》或重于泰山，或轻于鸿毛∶皆言轻也。脉以毛名者，为其重按即无，轻取则得也。
《素》玉机真脏秋脉者肺也，故其气来轻虚以浮，来急去散，故曰浮，《脉经》肺脉来泛泛
（《说文》浮，泛也。则泛泛，浮也。）而轻，如微风吹鸟背上毛。然则浮之轻，而重按即无
者，乃为正毛脉矣。其轻而不甚浮起，或浮之轻而沉候又兼他象者，只可谓之轻，不得谓之
毛。《脉经》于吐衄曰脉来轻轻在肌肉。此轻在中候，故不云毛也。于妇人妊娠曰按之则滑
，浮之则轻。此以沉候有他象，故亦不云毛也。言轻不足以该浮，言浮不足以该轻，故《伤
寒论》叠称之曰毛浮。
古说脉代有数种。《素》宣明五气脾脉代，注∶软而弱也。案软弱则气未尽畅，有乍数
乍疏
之意，此与《灵》邪气脏腑病形黄者，其脉代，皆谓脾之平脉。以《脉经》脾平脉长长而弱
，来疏去数参之，则此所云代，实即乍数乍疏之义。盖有数有疏，则气不调匀，如相更代，
故曰代，而古因谓不调之脉为代。《史记》仓公传∶和即经主病，代则络脉有过。以代对和
，则代为不调可知。《素·三部九候》中部乍数乍疏者死，其脉代而钩者，病在络脉，亦谓
不调者为代。承上句乍疏乍数而言，意谓经代死，终代病。夏气在络，长夏同法，故脾以代
为正，此与仓公说皆取脾平脉之代，而于非时妄见者，射其主病也。所以谓之代者，取其变
更不常，如四时代更，日月代明，父子代嬗，盛衰代迁之比。《说文》∶代，更也是也。代
之本义，并不取乎止，第以纯软弱则或不能行，有疏数则似可得间，间者止也。不能行亦止
也。故古因又谓脉之有止者为代，如经所云数动一代，五十动一代，乃“代”字之引伸义。
所以引代于止者，即动以观止则见为数，即止以观动则见为数，仍是乍疏乍数之意也。然犹
通
指一止者为代也。至仲景而下，别代于结，始以动而中止，不能自还，为代之专称矣。至李
时珍而下，别代于促、结，始以止有常数，为代之专称矣。于此见古今号之沿革。
古人用“毛”来比喻轻。《诗经·大雅》中说“德如毛”，意指轻；《孟子》中用一根羽毛与百钧重物相对比，又说金属重于羽毛；《汉书》中说有的重于泰山，有的轻于鸿毛：这些都是指轻。脉象以“毛”命名的原因，是因为重按时脉搏消失，轻取时才能感觉到。
《素问·玉机真脏论》中提到秋季的肺脉，其气轻虚而浮，来势急而去势散，所以称为浮脉，《脉经》描述肺脉来时泛泛（《说文解字》解释：浮，即泛。所以泛泛就是浮的意思）且轻，就像微风吹拂鸟背上的羽毛。那么，这种轻取可得、重按即无的脉象，才是标准的毛脉。那些轻而不甚浮起，或者轻取虽轻但沉候兼有其他脉象特征的，只能称为“轻”，不能称为“毛”。《脉经》在论述吐血、衄血时说“脉来轻轻在肌肉”，这是轻在中候，所以不称毛。在论述妇女妊娠时说“按之则滑，浮之则轻”，这是因为沉候有其他脉象，所以也不称毛。说“轻”不足以概括“浮”，说“浮”不足以概括“轻”，所以《伤寒论》中反复称其为“毛浮”。
古人对“代脉”的说法有多种。《素问·宣明五气》中说脾脉为代，注解说：软弱无力。案：软弱意味着气机未尽通畅，有忽快忽慢的意思，这与《灵枢·邪气脏腑病形》中说黄疸病患者脉代，都是指脾的平脉（正常脉象）。结合《脉经》中脾平脉长长而弱，来势疏缓去势急促来看，这里所说的“代”，实际上就是忽快忽慢的意思。因为有时快有时慢，所以气不调匀，如同相互更替，因此称为代，古人因而将不调匀的脉象称为代脉。《史记·仓公传》记载：和脉对应经脉主病，代脉对应络脉有过失。以代脉对和脉，可知代脉即为不调。《素问·三部九候》中说中部脉乍数乍疏者死，脉代而钩者，病在络脉，也是指不调者为代。承接上句乍疏乍数而言，意思是经脉代则死，终脉代则病。夏气在络脉，长夏同理，所以脾以代脉为正脉，这与仓公的说法都取脾平脉中的代脉，而对于非时令出现的代脉，则是射向其主病。之所以称之为代，是取其变化无常，如同四季更替、日月交替、父子传承、盛衰变迁等比喻。《说文解字》说：代，就是更替，正是这个意思。“代”的本义，并不取停止之意，只是纯软弱则可能无法运行，有疏数则似乎可得间隙，间隙即是停止。无法运行也是停止。所以古人又将脉中有停顿的称为代，如经典中所说的“数动一代”、“五十动一代”，乃是“代”字的引申义。之所以将“代”引申为停止，是因为通过跳动看停止则显得为数（快），通过停止看跳动也显得为数（快），仍然是忽快忽慢的意思。然而仍然通指一次停顿为代。到了张仲景之后，将代脉与结脉区分开来，才开始以跳动中途停止、不能自行恢复作为代脉的专称。到了李时珍之后，将代脉与促脉、结脉区分开来，才开始以停顿有固定规律作为代脉的专称。由此可见古今称谓的沿革演变。
The ancients used "mao" (hair) as a metaphor for lightness. In the *Book of Songs* (*Shijing*), Great Odes, it says "virtue is like hair," indicating lightness; in *Mencius*, a single feather is contrasted with a hundred jun (a unit of weight), and it is also stated that metal is heavier than feathers; in the *Book of Han*, some are heavier than Mount Tai, while others are lighter than goose down: all these refer to lightness. The pulse is named "mao" because it disappears upon heavy pressure but can be felt with light pressure.
In *Suwen: Yuji Zhenzang Lun* (Treatise on the Jade Machine and True Visceral Pulse), it states that the autumnal lung pulse comes lightly, void, and floating, arriving swiftly and dispersing quickly, hence it is called "floating" (Fu). The *Mai Jing* (Classic of Pulse Diagnosis) describes the lung pulse as coming "fanfan" (interpreted in *Shuowen Jiezi*: "Fu" means "Fan"; thus "fanfan" implies floating) and light, like a gentle breeze blowing the feathers on a bird's back. Therefore, the pulse that is light upon superficial palpation and vanishes upon deep pressure is the standard "mao" pulse. Those that are light but not significantly floating, or those that are light upon superficial palpation but exhibit other characteristics upon deep palpation, can only be termed "qing" (light) and not "mao." When discussing hematemesis and epistaxis, the *Mai Jing* states "the pulse comes lightly within the muscle layer." This indicates lightness at the middle level, hence it is not called "mao." When discussing pregnancy in women, it states "upon pressing it is slippery, upon floating it is light." Because there are other characteristics at the deep level, it is also not called "mao." Saying "light" is insufficient to encompass "floating," and saying "floating" is insufficient to encompass "light," therefore the *Shanghan Lun* (Treatise on Cold Damage) repeatedly refers to it as "mao fu" (light floating).
Ancient texts present several interpretations of the "dai" (intermittent/replacing) pulse. *Suwen: Xuanming Wuqi* states that the spleen pulse is dai, with annotations explaining it as soft and weak. Analysis shows that softness and weakness imply that qi flow is not fully smooth, suggesting irregularities in rate (now rapid, now slow). This aligns with *Ling Shu: Xieqi Zangfu Bingxing*, which states that patients with jaundice have a dai pulse, both referring to the normal pulse of the spleen. Cross-referencing with the *Mai Jing*, which describes the normal spleen pulse as long and weak, arriving slowly and departing rapidly, confirms that the "dai" mentioned here essentially means irregularity in rate (alternating between rapid and slow). Since there are periods of rapidity and slowness, the qi is not uniform, resembling mutual replacement, hence it is called "dai." Consequently, the ancients referred to irregular pulses as "dai." The *Records of the Grand Historian* (*Shiji*) in the biography of Cang Gong states: "He" (harmonious) corresponds to disease in the meridians, while "dai" corresponds to pathology in the collaterals. Contrasting "dai" with "he" reveals that "dai" signifies irregularity. *Suwen: Sanbu Jiuhou* states that death occurs if the central pulse is alternately rapid and slow, and disease in the collaterals is indicated by a dai pulse with a hook-like quality. This again defines "dai" as irregular. Following the previous statement about alternating rapidity and slowness, the meaning is that meridian dai leads to death, while terminal dai indicates disease. Summer qi resides in the collaterals, and the same logic applies to late summer; thus, the spleen considers the dai pulse as its normal state. This aligns with Cang Gong's view, taking the dai pulse of the normal spleen, whereas non-seasonal appearances of dai pulse indicate specific pathological conditions. The reason it is called "dai" is to evoke the concept of constant change, analogous to the succession of four seasons, the alternation of sun and moon, the transmission from father to son, and the shift between prosperity and decline. *Shuowen Jiezi* states: "Dai" means to replace/alternate, which is correct. The original meaning of "dai" does not imply stopping; rather, pure softness and weakness may hinder movement, while irregularities create intervals. An interval is a stop. Inability to move is also a stop. Thus, the ancients also referred to pulses with pauses as "dai." For example, classics mention "rapid movement with one pause" or "fifty movements with one pause," which are extended meanings of the character "dai." The reason "dai" was extended to mean stopping is that observing stops through movement appears rapid, and observing movement through stops also appears rapid, retaining the sense of alternating rapidity and slowness. However, it still generally refers to a single pause as "dai." It was not until Zhang Zhongjing that "dai" was distinguished from "jie" (knotted), beginning to define "dai" specifically as a pause during movement that cannot self-correct. It was not until Li Shizhen that "dai" was distinguished from "cu" (hasty) and "jie," beginning to define "dai" specifically by pauses occurring at regular intervals. This illustrates the evolution of terminology from ancient to modern times.