(次九针论之后)
五脏六腑之精气。皆上注于目而为之精。精之窠为眼。骨之精为瞳子。(属肾)筋之精为
黑眼
。(属肝)血之精为络。(属心)其窠气之精为白眼。(属肺)肌肉之精为约束。(属脾)裹撷筋骨
血气之精。而与脉并为系。上属于脑后出于项中。故邪中于项。因逢其身之虚。其入深。则
随眼系以入于脑。入于脑。则脑转。脑转则引目系急。目系急则目眩以转矣。邪(斜同)其精
。(睛同)其精所中不相比也则精散。精散则视岐。视岐见两物。目者心使也。心者神之舍也
。故精神乱而不转。卒然见非常处。精神魂魄散不相得。故曰惑也 心有所喜。神有所恶。
卒然相感。则精气乱。视误故惑神移乃复。是故间者为迷。甚者为惑。
上气不足。下气有余。肠胃实而心肺虚。虚则营卫留于于下。(阳衰)久之不以时上。故
善忘也。
精气并于脾。热气留于胃。胃热则消谷。谷消故善饥。胃气逆上则胃脘寒(不能营运。
则其中脘当寒)故不嗜食也(此言所以善饥而不嗜食也)
卫气不得入于阴。常留于阳。留于阳则阳气满。阳气满则阳跷盛不得入于阴。则阴气虚
。故
目不瞑矣。卫气留于阴不得行于阳。留于阴。则阴气盛。阴气盛。则阴跷满不得入于阳则阳
气虚。故目闭也。
夫卫气者。昼日常行于阳。夜行于阴。故阳气尽则卧。阴气尽则寤。故肠胃大。则卫气
行留
久。皮肤湿分肉不解则行迟留于阴也久。其气不精则欲瞑。故多卧矣。其肠胃小皮肤滑以缓
。分肉解利。卫气之留于阳也久。故少瞑焉。
（在《九针论》之后）
五脏六腑的精气，都向上灌注于眼睛，从而形成眼部的精气。精气的汇聚之处称为眼。其中，骨之精气表现为瞳子。（归属于肾）筋之精气表现为黑眼。（归属于肝）血之精气表现为络脉。（归属于心）气之精气在白眼的部分汇聚。（归属于肺）肌肉之精气表现为眼睑的约束功能。（归属于脾）这些包裹着筋骨、血气精气的物质，与脉络共同构成目系，向上连接至脑后，出于项部中间。所以，邪气侵袭项部，如果恰逢人体正气虚弱，邪气就会深入，顺着目系进入脑部。进入脑部后，会导致脑髓转动；脑髓转动则会牵引目系紧张；目系紧张就会导致头晕眼花。邪气侵入其精气之中，如果精气所受的损伤不能相互协调，那么精气就会散乱。精气散乱就会出现视物重影，看到两个物体。眼睛是心的使者，心是神志居住的处所。所以精神混乱而不能正常运作，突然看到不寻常的景象，精神、魂魄离散而不相协调，这就叫做“惑”。心中有所喜好，神志有所厌恶，突然受到感应，就会导致精气紊乱，视觉错误而产生迷惑。神志恢复正常后，迷惑才会消除。因此，症状轻微的称为“迷”，症状严重的称为“惑”。
上部的正气不足，下部的正气有余，肠胃充实而心肺虚弱。虚弱则营气和卫气滞留于下部。（阳气衰微）时间久了不能按时上行，所以容易健忘。
精气合并于脾，热气停留于胃。胃热则能消化食物，食物被消化得快所以容易饥饿。胃气逆而上行，则胃脘部寒冷（因为不能正常运化，所以胃脘部位感觉寒冷），所以不喜欢进食。（这段话解释了为什么既容易饥饿又不喜欢进食的原因）
卫气不能进入阴分，常常停留在阳分。停留在阳分则阳气满盛，阳气满盛则阳跷脉旺盛，无法进入阴分，导致阴气虚弱。所以眼睛无法闭合（失眠）。卫气停留在阴分，不能运行到阳分。停留在阴分则阴气盛，阴气盛则阴跷脉满盛，无法进入阳分，导致阳气虚弱。所以眼睛闭合（嗜睡）。
卫气，白天常运行于阳分，夜晚运行于阴分。所以阳气尽时则入睡，阴气尽时则醒来。如果肠胃大，卫气在体内停留的时间就久。如果皮肤湿润、分肉之间不解利，则卫气运行迟缓，在阴分停留的时间就久。如果人的精气不充足，就想睡觉，所以多卧（嗜睡）。如果肠胃小，皮肤滑润且分肉之间解利通畅，卫气在阳分停留的时间就久，所以少眠（睡眠时间短）。
(After the "Treatise on the Nine Needles")
The essence and qi of the five zang organs and six fu organs all ascend to the eyes, forming the essence of the eyes. The gathering place of this essence is the eye. The essence of bone manifests as the pupil. (Belongs to Kidney) The essence of sinew manifests as the black part of the eye (iris/cornea area). (Belongs to Liver) The essence of blood manifests as the collaterals. (Belongs to Heart) The essence of qi gathers in the white part of the eye. (Belongs to Lung) The essence of muscle manifests as the constraints (eyelids). (Belongs to Spleen) These substances, which envelop the essence of sinew, bone, blood, and qi, merge with the vessels to form the optic nerve system (mu xi), connecting upwards to the back of the head and emerging from the middle of the neck. Therefore, when pathogenic factors attack the neck, if coinciding with the body's deficiency, they penetrate deeply, following the optic nerve system into the brain. Upon entering the brain, it causes dizziness/rotation of the brain; rotation of the brain pulls the optic nerve system tight; tightness of the optic nerve system leads to vertigo and dizziness. If pathogenic factors invade its essence, and the damage to the essence cannot coordinate mutually, then the essence scatters. When the essence scatters, diplopia occurs, seeing double images. The eyes are the agents of the Heart; the Heart is the residence of Shen (Spirit). Therefore, when spirit and mind are chaotic and fail to function normally, suddenly seeing extraordinary scenes causes spirit, hun, and po to scatter and lose coordination, which is called "huo" (confusion/delusion). If the heart has preferences and shen has aversions, sudden stimulation causes chaos in essence and qi, leading to visual errors and confusion. Once shen returns to normal, the confusion resolves. Thus, mild cases are called "mi" (bewilderment), and severe cases are called "huo" (delusion/confusion).
When upper qi is insufficient and lower qi is excessive, the intestines and stomach are full while the heart and lungs are deficient. Deficiency causes ying (nutritive) and wei (defensive) qi to stagnate in the lower body. (Yang qi declines) Over time, failing to ascend timely, one becomes prone to forgetfulness.
Essence and qi merge into the Spleen, and hot qi lingers in the Stomach. Stomach heat promotes digestion; since food is digested quickly, one feels hungry easily. If Stomach qi rebels upward, the epigastrium becomes cold (because it fails to transport and transform properly, the epigastric region feels cold), thus one loses appetite. (This explains why one may feel hungry yet lack desire to eat.)
If wei (defensive) qi cannot enter the yin aspect, it often remains in the yang aspect. Remaining in yang makes yang qi abundant; abundant yang qi makes the Yang Qiao vessel vigorous, preventing entry into yin, resulting in yin qi deficiency. Hence, the eyes remain open (insomnia). If wei qi remains in yin and cannot travel to yang, remaining in yin makes yin qi abundant; abundant yin qi fills the Yin Qiao vessel, preventing entry into yang, resulting in yang qi deficiency. Hence, the eyes close (hypersomnia/sleepiness).
Wei qi travels through the yang aspect during the day and the yin aspect at night. Therefore, when yang qi exhausts, one sleeps; when yin qi exhausts, one wakes. If the intestines and stomach are large, wei qi stays inside for a long time. If the skin is moist and the intermuscular spaces are not smooth, movement is slow, causing wei qi to stay in yin for a long time. If one's qi is not robust, there is a desire to sleep, hence hypersomnia. If the intestines and stomach are small, the skin is smooth, and the intermuscular spaces are unobstructed, wei qi stays in yang for a long time, hence short sleep duration.