左寸，外以候心，内以候膻中。 右寸，外以候肺，内以候胸中。
左关，外以候肝，内以候膈中。 右关，外以候脾，内以候胃脘。
左尺，外以候肾，内以候腹中。 右尺，外以候心主，内以候腰。
释曰∶六脏，六腑，十二经络，候之无逾三部。要之，前布六经，乃候淫邪外入，自经
络而及于脏；后说六脏，乃候情意内郁，自脏腑出而应于经。内外所因，颖然明白，学诊之
道，当自此始。外因虽自经络而入，必及于脏，须识五脏部位；内因郁满于中，必应于经，
亦须徇经说证，不可偏局。故《经》云∶上竟上，胸喉中事也；下竟下，腰足中事也。不可
不通。
人之脉者，乃血之隧道也，非气使则不能行，故血为脉，气为息，脉息之名，自是而分
。呼吸者，气之橐 ；动应者，血之波澜。其经以身寸度之，计十六丈二尺。一呼，脉
再动，一吸，脉再动；呼吸定息，脉五动；闰以太息，则六动。一动一寸，故一息脉行六寸
，十息六尺，百息六丈，二百息十二丈，七十息四丈二尺，计二百七十息，漏水下二刻，尽
十六丈二尺，营周一身。百刻之中，得五十营。故曰，脉行阳二十五度，行阴二十五度也。
息者以呼吸定之，一日计一万三千五百息，呼吸进退，既迟于脉，故八息三分三毫三厘，方
行一寸，八十三息三分三毫行一尺，八百三十三息三分行一丈，八千三百三十三息行十丈，
余六丈二尺，计五千一百六十七息，通计一万三千五百息，方行尽十六丈二尺，经络气周于
一身，一日一夜大会于风府者是也。脉属阴，阴行速，犹太阴一月一周天；息属阳，阳行迟
，犹太阳一岁一周天，如是则应天常度。故春肝脉弦细而长，夏心脉浮大而洪，长夏脾脉软
大而缓，秋肺脉浮涩而短，冬肾脉沉濡而滑。各以其时而候旺相休囚，脉息无不及太过之患
，故曰平人。平人常气禀于胃，必以胃气为本，取其资成也。合本脏气三分，微似弦洪缓涩
沉，则为平脉。若真脏脉见，则不佳矣。广如后说。
左寸口脉，外部用以候察心，内部用以候察膻中。右寸口脉，外部用以候察肺，内部用以候察胸中。
左关部脉，外部用以候察肝，内部用以候察膈中。右关部脉，外部用以候察脾，内部用以候察胃脘。
左尺部脉，外部用以候察肾，内部用以候察腹中。右尺部脉，外部用以候察心主（心包络），内部用以候察腰部。
注释说：六脏、六腑以及十二经络，诊察它们没有超出寸、关、尺三部脉的范围。总之，前面论述的六经，是用来候察淫邪从外部侵入，由经络进而波及脏腑；后面论述的六脏，是用来候察情志内郁，由脏腑发出而应验于经络。外因和内因，清晰明白，学习诊脉之道，应当从这里开始。外因虽然从经络进入，必定会波及到脏腑，必须认识五脏的部位；内因郁结充满于体内，必定会应验于经络，也必须顺着经络来叙述证候，不可偏执局限。所以《内经》说：上部脉象反映到头竟之上，是胸和喉中的事情；下部脉象反映到尾闾之下，是腰和足中的事情。不可以不通晓。
人的脉管，是血液运行的通道，不是气的推动就不能运行，所以血构成脉，气构成息，脉和息的名称，由此而区分。呼吸，是气的鼓动（如风箱）；脉搏跳动，是血的波澜。经脉的长度用身体同身寸来度量，共计十六丈二尺。一次呼气，脉搏跳动两次；一次吸气，脉搏跳动两次；一呼一吸之间称为“定息”，脉搏跳动五次；加上偶尔的长息（太息），则跳动六次。每次跳动一寸，所以一息脉搏运行六寸，十息运行六尺，百息运行六丈，二百息运行十二丈，七十息运行四丈二尺，共计二百七十息，漏壶滴水下降二刻，运行完十六丈二尺，环绕全身一周。在一百刻的时间内，完成五十周循环。所以说，脉行于阳分二十五度，行于阴分二十五度。
息是以呼吸来计算的，一天共计一万三千五百息。呼吸的进退，比脉的运行稍慢，所以八息又三分三毫三厘，才运行一寸；八十三息又三分三毫，运行一尺；八百三十三息又三分，运行一丈；八千三百三十三息运行十丈；剩下的六丈二尺，共计五千一百六十七息，通计一万三千五百息，才运行完十六丈二尺，经络之气环绕全身，一天一夜在风府穴大会，就是这种情况。脉属于阴，阴行速度快，就像太阴（月亮）一个月绕天一周；息属于阳，阳行速度慢，就像太阳一年绕天一周，这样就能顺应天的常规度数。所以春季肝脉弦细而长，夏季心脉浮大而洪，长夏脾脉软大而缓，秋季肺脉浮涩而短，冬季肾脉沉濡而滑。各以其对应的时令来候察旺、相、休、囚的状态，脉息没有不及或太过之患，所以称为平人（健康人）。平人的常气禀受于胃，必须以胃气为本，取法于它的资助成就。结合本脏之气占三分，微带有弦、洪、缓、涩、沉的特征，则为平脉。如果出现真脏脉，就不好了。详细情况见后文解说。
The left Cun (Cun position, radial artery) pulse externally indicates the Heart, and internally indicates the Danzhong (Pericardium region). The right Cun pulse externally indicates the Lung, and internally indicates the Chest center.
The left Guan (Guan position, radial artery) pulse externally indicates the Liver, and internally indicates the Diaphragm center. The right Guan pulse externally indicates the Spleen, and internally indicates the Stomach cavity.
The left Chi (Chi position, radial artery) pulse externally indicates the Kidney, and internally indicates the Abdomen center. The right Chi pulse externally indicates the Xin Zhu (Heart Master/Pericardium), and internally indicates the Waist.
Commentary: The six Zang organs, six Fu organs, and twelve meridians are all examined without exceeding the three positions of Cun, Guan, and Chi. In summary, the preceding discussion of the Six Channels is for examining pathogenic factors entering from the exterior, moving from the meridians to the Zang organs; the subsequent discussion of the six Zang organs is for examining internal emotional stagnation, manifesting from the Zang-Fu organs to the meridians. The external and internal causes are clearly distinguished. The way of learning diagnosis should begin here. Although external causes enter via the meridians, they must eventually affect the Zang organs, so one must understand the locations of the five Zang organs. Internal causes stagnate within, but must manifest in the meridians, so one must follow the meridian theory to describe symptoms, avoiding partiality. Thus, the *Classic* states: "Upper reaches the upper, concerning the chest and throat; lower reaches the lower, concerning the waist and feet." This must not be ignored.
Human vessels are the tunnels through which blood flows; without the driving force of Qi, blood cannot move. Therefore, blood constitutes the Mai (Pulse/Vessel), and Qi constitutes the Xi (Breath/Pulse rate), and the terms Mai and Xi are distinguished thereby. Respiration is the bellows of Qi; the pulsation is the waves of blood. The meridians are measured by body inches, totaling sixteen zhang and two chi. With each exhalation, the pulse beats twice; with each inhalation, the pulse beats twice. At the pause between breaths (Ding Xi), the pulse beats five times; including occasional deep sighs (Tai Xi), it beats six times. Each beat covers one cun, so in one respiratory cycle, the pulse travels six cun. In ten cycles, it travels six chi; in a hundred cycles, six zhang; in two hundred cycles, twelve zhang; in seventy cycles, four zhang and two chi. A total of two hundred seventy cycles correspond to two ke (water clock units) of water dripping, completing sixteen zhang and two chi, circling the entire body. Within one hundred ke, fifty circuits are completed. Thus it is said that the pulse travels twenty-five degrees in Yang and twenty-five degrees in Yin.
Respiration is calculated by breaths, totaling thirteen thousand five hundred per day. The advance and retreat of respiration are slightly slower than the pulse. Specifically, eight breaths plus three fen, three hao, and three li are required to travel one cun; eighty-three breaths plus three fen and three hao travel one chi; eight hundred thirty-three breaths plus three fen travel one zhang; eight thousand three hundred thirty-three breaths travel ten zhang. The remaining six zhang and two chi require five thousand one hundred sixty-seven breaths. In total, thirteen thousand five hundred breaths complete the circulation of sixteen zhang and two chi. The Qi of the meridians circulates the whole body, gathering at the Fengfu point once a day and night. The pulse belongs to Yin, and Yin moves quickly, like the Taiyin (Lunar cycle) circling the heavens once a month. Respiration belongs to Yang, and Yang moves slowly, like the Taiyang (Solar cycle) circling the heavens once a year. This conforms to the constant laws of Heaven. Thus, in Spring, the Liver pulse is Xian (Wiry), thin, and long; in Summer, the Heart pulse is Fu (Floating), large, and Hong (Surging); in Late Summer, the Spleen pulse is Ruan (Soft), large, and Huan (Moderate); in Autumn, the Lung pulse is Fu (Floating), Se (Choppy), and Duan (Short); in Winter, the Kidney pulse is Chen (Deep), Ru (Soggy), and Hua (Slippery). One observes their Wang (Prosperous), Xiang (Secondary), Xiu (Resting), and Qiu (Imprisoned) states according to the season. When the pulse and breath have neither deficiency nor excess, the person is called Ping Ren (Healthy Person). The normal Qi of a healthy person is derived from the Stomach, making Stomach Qi the root, taking its nourishment and completion. Combining this with the specific Qi of the respective Zang organ (occupying three parts), if there is a slight trace of Xian, Hong, Huan, Se, or Chen, it is considered a Ping Mai (Normal Pulse). If the True Zang Pulse appears, it is unfavorable. For details, see the following explanation.