罗东逸曰，人身之正，有三阴三阳之经，分主周身。然其经皆起于足，三阳为外，三阴为内。
故足太阳之经，从巅顶头项而下五行，居身之背，以至于足。足阳明从额颅颈喉而下，亦五行，居身之前
，以至于足。足少阳从耳前后下胁身畔，
而居身之两胁，以至于足，此足三阳之周身，所以主外也。至于三阴，足太阴为后天六经之主，足少阴为
先天藏精之腑，足厥阴为阴阳生气之根，所以立人之命蒂者，尽足三阴也。
若手之六经，虽与足六经出入相连，而手少阴心，君主清静高拱，太阴肺调元行气，包络为佐贰臣
，二肠三焦，器能传化之官耳。其经位则见于两臂，地既不多，而所伤之病皆自足六经及之。此仲景于伤
寒止立足六经，而不立手经，为古圣传述，为后学发蒙也。
盖手六经缘与足六经相络上下，故详之十二经。其实此六经之阴阳，皆足六经之附庸也。末学不
察，见古经三阳之文，遂以膀胱与小肠双举，二阳则大肠与胃双举，辄以附庸为主用，轻重失宜。不知手
经缘与足经相接，非谓附庸能与天运四时同体也。此义不明，乃自命为名家者，亦堕此云雾，为之一概。
脉有阴阳，知阳者知阴，知阴者知阳。凡阳有五，五五二十五阳。所谓阴者，真脏也，见则必败，
败必死也；所谓阳者，胃脘之阳也。别于阳者，知病处也；别于阴者，知死生之期。
所谓阴阳者，去者为阴，至者为阳，静者为阴，动者为阳；迟者为阴，数者为阳。
脉有逆从四时，未有藏形，春夏而脉瘦，秋冬而脉浮大，命曰逆四时也。风热而脉静，泄而脱血脉实
，病在中脉虚，病在外脉涩坚者，皆难治，命曰反四时也。
其脉绝不来，若一息五六至，其形肉不脱，真脏虽不见，犹死也。
逆从之例三条，一以反四时，一以反病体，一以形脉相反。凡逆从之见有余不足轻重，皆可知矣。
按阴阳逆从四字，是诊脉辨病之要法。诸脉异等，脏腑异情，四时异宜，死生之辨，皆以此四字别之
。故胃气、四时、五脏诸脉之形，为诊家之经；阴阳逆从，为诊家之纬。
罗东逸说，人体正常的生理结构，由三阴经和三阳经组成，分别主管全身。然而这些经脉都起始于足部，三阳经位于体表外部，三阴经位于体内内部。
所以足太阳膀胱经，从头顶头项部位向下分为五行（五条循行路线），居于身体背部，一直延伸到足部。足阳明胃经从额颅、颈部、咽喉向下，也分为五行，居于身体前面，一直延伸到足部。足少阳胆经从耳前耳后向下经过胁肋和身体侧面，居于身体两侧胁肋部位，一直延伸到足部，这就是足三阳经遍布全身，所以主司体表的防御功能。至于三阴经，足太阴脾经是后天六经的主宰，足少阴肾经是先天主藏精气的脏腑，足厥阴肝经是阴阳生气的根本，所以确立人的生命根基的，全靠足三阴经。
至于手部的六条经脉，虽然与足部六条经脉出入相连，但手少阴心经作为君主之官，清静高拱而不轻易受邪；手太阴肺经调节元气运行气机；心包络作为辅佐之臣；大肠、小肠和三焦，只是负责传导和变化的器官罢了。它们的经脉位置只见于两臂，占据的空间既不大，而且所受的病邪也都源自足部六经的影响。这就是张仲景在《伤寒论》中只立足部六经来论述，而不设立手部经脉，是为了遵循古代圣人的传承，为了启发后学者的蒙昧。
大概手部六经因为与足部六经上下相互联络，所以在论述十二经脉时会详细提及。其实这手部六经的阴阳属性，都只是足部六经的附属部分。末流学者不加考察，看到古经文中关于三阳经的记载，就把膀胱经与小肠经并列，把大肠经与胃经并列，往往以附属部分作为主要作用，轻重失当。不知道手经之所以与足经相接，并不是说附属部分能与天运四时同为一体。这个道理如果不明白，那些自命为名家的人，也会陷入这种迷雾之中，一概而论。
脉象有阴阳之分，懂得阳脉就能懂得阴脉，懂得阴脉就能懂得阳脉。凡是阳脉有五种类型，五五相乘共有二十五种阳脉表现。所谓阴脉，是指真脏脉，如果出现真脏脉，说明胃气已败，出现真脏脉必定死亡；所谓阳脉，是指胃脘部的阳气（即胃气）。辨别出阳脉（胃气）的存在，就能知道病变的部位；辨别出阴脉（真脏脉）的出现，就能判断死亡的期限。
所谓阴阳，脉搏离去的方向属阴，到来的方向属阳；静止的脉象属阴，跳动的脉象属阳；迟慢的脉象属阴，快速的脉象属阳。
脉象有顺应或违背四时的情况，如果没有五脏的真脏脉显现，但在春夏季节脉象反而瘦小，在秋冬季节脉象反而浮大，这叫做违背四时规律。感受风热之邪而脉象反而沉静，腹泻且脱血而脉象反而实大，病位在内部而脉象反而虚弱，病位在外部而脉象反而涩滞坚硬的，都属于难治之症，这叫做违背四时规律。
如果脉搏完全断绝不来，或者一呼一吸之间跳动五六次，虽然形体肌肉没有消瘦，真脏脉虽然没有显现，但也属于死证。
逆从的例子有三条：一是违背四时规律，二是违背疾病本身体质，三是形态与脉象相反。凡是见到逆从现象，结合有余不足、轻重的情况，都可以判断出来了。
按照阴阳逆从这四个字，是诊脉辨病的关键方法。各种脉象不同等级，脏腑情况各异，四时适宜不同，生死界限的辨别，都通过这四个字来区分。所以胃气、四时、五脏各脉的形态，是诊脉家的经典依据；阴阳逆从，是诊脉家的经纬法则。
Luo Dongyi stated that the normal physiological structure of the human body consists of the Three Yin (Taiyin, Shaoyin, Jueyin) and Three Yang (Taiyang, Yangming, Shaoyang) meridians, which respectively govern the entire body. However, all these meridians originate from the feet; the Three Yang meridians are located externally on the surface, while the Three Yin meridians are located internally within the body.
Therefore, the Foot-Taiyang Bladder Meridian descends from the vertex and head/neck region in five parallel lines, occupying the back of the body, extending down to the foot. The Foot-Yangming Stomach Meridian descends from the forehead, skull, neck, and throat, also in five lines, occupying the anterior aspect of the body, extending down to the foot. The Foot-Shaoyang Gallbladder Meridian descends from the front and back of the ears, passing through the hypochondrium and lateral aspects of the body, occupying the bilateral hypochondriac regions, extending down to the foot. This distribution of the Foot-Three Yang meridians throughout the body is why they primarily govern the exterior defense. As for the Three Yin meridians, the Foot-Taiyin Spleen Meridian is the master of the postnatal Six Meridians; the Foot-Shaoyin Kidney Meridian is the zang organ responsible for storing essence as the先天 (innate/congenital) foundation; and the Foot-Jueyin Liver Meridian is the root of the vital energy of Yin and Yang. Thus, the establishment of the foundation of human life relies entirely on the Foot-Three Yin meridians.
Regarding the six meridians of the hand, although they connect and interlink with the six meridians of the foot, the Hand-Shaoyin Heart Meridian, as the Monarch organ, remains clear, quiet, and high above, not easily affected by pathogens; the Hand-Taiyin Lung Meridian regulates primordial Qi and moves Qi mechanisms; the Pericardium acts as an assisting minister; and the Large Intestine, Small Intestine, and Sanjiao (Triple Burner) are merely organs responsible for transmission and transformation. Their meridian pathways are only visible in the two arms, occupying a relatively small space, and the diseases they suffer from generally stem from the influence of the Foot-Six Meridians. This is why Zhang Zhongjing, in his Treatise on Cold Damage (Shanghan Lun), established only the Foot-Six Meridians for discussion and did not establish separate chapters for the Hand meridians, thereby following the transmission of ancient sages and enlightening later learners.
Generally, because the Hand-Six Meridians are interconnected with the Foot-Six Meridians up and down, they are detailed when discussing the Twelve Primary Meridians. In reality, the Yin and Yang attributes of these Hand-Six Meridians are merely vassals or appendages to the Foot-Six Meridians. Scholars of later generations, failing to investigate this, see the texts regarding the Three Yang meridians in ancient classics and pair the Bladder Meridian with the Small Intestine Meridian, and the Large Intestine Meridian with the Stomach Meridian. They often treat these appendages as primary functions, misjudging the weight and importance. They fail to understand that the connection between Hand and Foot meridians does not imply that the appendages can share the same nature as the Heavenly movements and Four Seasons. If this principle is not understood, even those who claim to be masters fall into this fog and generalize indiscriminately.
Pulse qualities have Yin and Yang distinctions; knowing Yang allows one to know Yin, and knowing Yin allows one to know Yang. There are five types of Yang pulses, and five times five yields twenty-five Yang pulse manifestations. What is referred to as "Yin" here is the Zang Organ Pulse (True Zang Pulse); if such a pulse appears, it indicates failure, and its appearance signifies death. What is referred to as "Yang" here is the Yang of the Stomach House (i.e., Stomach Qi). Distinguishing the presence of Yang (Stomach Qi) allows one to locate the disease; distinguishing the appearance of Yin (True Zang Pulse) allows one to predict the time of death.
What is meant by Yin and Yang [in pulse diagnosis] is: the direction away from the heart is Yin, the direction towards the heart is Yang; stillness is Yin, movement is Yang; slowness is Yin, rapidity is Yang.
Pulses may follow or oppose the Four Seasons. If there are no True Zang Pulse forms present, but the pulse is thin/small during Spring and Summer, and floating/large during Autumn and Winter, this is called opposing the Four Seasons. If wind-heat is present but the pulse is still/deep, or if diarrhea and blood loss occur but the pulse is excess/full, or if the disease is internal but the pulse is deficient, or if the disease is external but the pulse is choppy and firm, all these are difficult to treat and are called opposing the Four Seasons.
If the pulse completely ceases to come, or if there are five to six beats per respiration cycle, and although the flesh has not wasted away and the True Zang Pulse has not yet appeared, it is still a death case.
There are three examples of opposition and compliance: one is opposing the Four Seasons, one is opposing the physical constitution of the disease, and one is the opposition between form and pulse. By observing these signs of opposition/compliance along with excess/deficiency and severity, prognosis can be determined.
The four characters "Yin, Yang, Opposition, Compliance" are the essential methods for pulse diagnosis and disease differentiation. Various pulse categories differ, Zang-Fu conditions vary, and seasonal appropriatenesses change; the distinction between life and death is all differentiated by these four characters. Therefore, the forms of Stomach Qi, Four Seasons, and Five Zang pulses constitute the classic basis for pulse diagnosticians; Yin, Yang, Opposition, and Compliance serve as their guiding principles (warp and weft).