所谓元精，非津液脂髓之精。元气，非呼吸吐纳之气。元神，非知觉运动之神。元精顺可生子，逆
可成仙。能采阴阳之菁英，结成为精，生亦能变化无穷，神通广大，但落于有形，终属后天之物。上清世
界难容，生时不过能养性灵，去后不过能保躯壳。至若元气，元神，既经元精，存养多年，功行圆满。神
用之，则放大光明，亿万化身；敛之则如混沌一元。气用之，则风云雷雨，变态无端，藏之，则与太虚一
体。元精足，获元气元神。不能随元气送元神上升。丹家所以炼元精者，为养元气元神故也。就即生时
观之，元气元神，活活泼泼，虚虚实实，不即不离，极明极灵。元神为元精主宰，元气作元精驱使，神气之
重，更不待辨而可明矣。
人聚五行之精而生，必藉五行所化而养。人身之有元精，如五谷中之有稻米。种于春，长于夏，
结实于秋，得纯阳之气，又根养于水，花扬于午，藉水火既济而生，炼以三伏烈日之气而成，所以养人
之物，稻米为上，足补人身阴阳结成之元精。至五行所化，青黄赤白黑，咸苦酸辛甘之物。五行所属，
东西南北中之产，皆非纯阴纯阳，辅助元精则可，生养元精，则不能。可用以治五脏六腑十二经络之病，
不能补元阳真阴之不足。元精未曾炼到蒸之为液，敛之为髓，散之为体，浸之为血，化之为气，用之为
神时候，正宜努力加餐，必待元精充实，始减去五味，每日素餐。渐至元精凝结，可撤去菜蔬，专食熟饭。
久久元向导活，渐有生发，即可炼精。熟米凉水，淘净瓦器盛贮，瓦盖紧覆，毋使出气，弥封笋缝，下
以柴火熏之，浅水烘干，每食以胡麻松子下之，
先熟食，后冷餐，渐渐生食，渐渐减食，渐渐专食胡麻松子，渐渐减食胡麻松子，渐渐不食，方能
辟谷，服气不食。若有麦无稻，先调和后，净面先荤食，后素食，先菜下、后胡麻松子下，减食，
熟食；熟食、冷食、不食，次第同，功夫至此，已到中乘。到底不懈，足登上乘。世人一念于道，劝
欲辟谷，即求代餐，致生怪疾，是循末忘本之故也。
所谓元精，并非指津液、脂肪和骨髓中的精微物质。元气，并非指呼吸吐纳之气。元神，并非指知觉与运动之神识。元精顺着生理规律可以生育子女，逆着修炼法则可以成就仙道。若能采集阴阳的精华，凝结成为元精，其生命力便能变化无穷，神通广大，但既然落入有形之体，终究属于后天的事物。上清仙境难以容纳它，活着时不过能修养性灵，死后也不过能保全躯壳。至于元气和元神，是在元精经过多年存养、功夫圆满之后才具备的。元神发挥作用时，能放射出万丈光明，化身亿万；收敛起来则如同混沌未分的统一体。元气发挥作用时，能引发风云雷雨，变幻莫测；隐藏起来，则与太虚融为一体。只有元精充足，才能获得元气和元神。如果元精不能随着元气将元神输送上升，丹家之所以修炼元精，正是为了涵养元气和元神啊。就生命存在时的状态来看，元气和元神活泼灵动，似虚似实，不即不离，极其明亮且充满灵性。元神是元精的主宰，元气受元精驱使，神与气的重要性，不用辨析就可以明白。
人聚集五行之精而生，必须依靠五行所化生的食物来滋养。人体内的元精，就像五谷中的稻米一样。稻米春天播种，夏天生长，秋天结实，吸收纯阳之气，根部在水中滋养，花朵在正午开放，借助水火既济的原理生长，经三伏烈日的炼化而成。因此，作为滋养人的食物，稻米是最好的，足以补充人体内阴阳结合而成的元精。至于五行所化生的青、黄、赤、白、黑五种颜色，以及咸、苦、酸、辛、甘五种味道的事物，还有东西南北中五个方位出产的食物，都不是纯阴或纯阳之物，它们只能辅助元精，而不能直接生养元精。这些食物可以用来治疗五脏六腑和十二经络的疾病，但不能补充元阳和真阴的不足。在元精尚未修炼到“蒸之为液、敛之为髓、散之为体、浸之为血、化之为气、用之为神”的阶段时，正应该努力进食（正常饮食），必须等到元精充实之后，才开始减少五味杂食，每日吃素食。逐渐地，当元精凝结稳固时，可以撤去蔬菜，只吃熟米饭。久而久之，元气导引通畅，逐渐产生生机发越，就可以开始炼精了。具体方法是：将熟米用凉水淘净，盛放在瓦器中，用瓦片紧密覆盖，防止漏气，用笋皮密封缝隙，下面用柴火熏烤，浅水烘干。每次食用时，用胡麻和松子送服。先吃熟食，再吃冷食，逐渐过渡到生食，逐渐减少食量，逐渐只吃胡麻和松子，再逐渐减少胡麻和松子的摄入，最后完全不吃，这样才能达到辟谷的境界，只服气而不进食。如果没有稻米而有麦子，顺序调整为：先调和面食，洗脸后先吃荤食，后吃素食，先用菜送服，后用胡麻松子送服，逐渐减少食量，改为熟食；熟食、冷食、不食的次第相同。功夫做到这一步，已达到中乘境界。若能始终不懈怠，足以上达上乘境界。世人一旦立志修道，劝人辟谷，却急于寻找代餐食物，导致生出怪病，这是舍本逐末的缘故。
The so-called Yuanjing (Primordial Essence, 元精) is not the essence found in body fluids (Jinye, 津液), fat, or bone marrow. Yuanqi (Primordial Qi, 元气) is not the qi of breathing and exhalation. Yuanshen (Primordial Spirit, 元神) is not the spirit of perception and movement. Yuanjing, following the natural order, can generate offspring; reversing this process through cultivation can lead to immortality. By collecting the quintessence of Yin and Yang and condensing it into Yuanjing, one’s vitality can transform infinitely and manifest great spiritual powers. However, once it falls into a tangible form, it ultimately belongs to post-heavenly things. It cannot be accommodated in the Upper Clarity Realm; while alive, it merely nourishes the nature and spirit, and after death, it only preserves the physical shell. As for Yuanqi and Yuanshen, they are attained only after Yuanjing has been stored and nourished for many years, until the practice is complete. When Yuanshen is utilized, it emits brilliant light and manifests billions of avatars; when gathered inward, it resembles the undifferentiated chaos of the One. When Yuanqi is utilized, it generates wind, clouds, thunder, and rain with unpredictable transformations; when hidden, it becomes one with the Great Void. Only when Yuanjing is sufficient can one acquire Yuanqi and Yuanshen. If Yuanjing cannot send Yuanshen upward along with Yuanqi, then the reason Daoist alchemists refine Yuanjing is precisely to nourish Yuanqi and Yuanshen. Observing the state of life, Yuanqi and Yuanshen are lively and vivid, seemingly empty yet substantial, neither attached nor detached, extremely bright and spiritually agile. Yuanshen is the master of Yuanjing, and Yuanqi is driven by Yuanjing; the weight and importance of Shen (Spirit) and Qi are evident without further debate.
Humans are born from the essence of the Five Elements and must be nourished by what the Five Elements transform into. The Yuanjing in the human body is like rice among the five grains. Planted in spring, it grows in summer, bears fruit in autumn, absorbs pure Yang qi, is nourished at the roots by water, blooms at noon, and is generated through the mutual interaction of Water and Fire (Shuihuo Jiji, 水火既济), refined by the intense heat of the dog days of summer. Therefore, among foods that nourish humans, rice is superior, as it sufficiently supplements the Yuanjing formed by the union of Yin and Yang in the body. Regarding things transformed by the Five Elements—those of green, yellow, red, white, and black colors; salty, bitter, sour, pungent, and sweet tastes; and products from the East, West, South, North, and Center—they are neither purely Yin nor purely Yang. They can assist Yuanjing but cannot directly generate or nourish it. Such foods can treat diseases of the Zang-Fu organs (Zang-Fu Organs, 脏腑) and the twelve meridians (Twelve Meridians, 十二经络), but they cannot supplement the deficiency of True Yuan Yang (True Primordial Yang, 元阳) and True Yin (True Primordial Yin, 真阴). While Yuanjing has not yet been refined to the stage where it "transforms into fluid when steamed, condenses into marrow when gathered, disperses into the body, soaks into blood, transforms into qi, and is used as spirit," one should strive to eat normally. Only after Yuanjing is full should one reduce the five flavors and consume a vegetarian diet daily. Gradually, when Yuanjing condenses and stabilizes, vegetables can be removed, eating only cooked rice. Over time, as the guiding flow of qi becomes smooth and vitality begins to sprout, one can begin refining Jing (Essence, 精). The method is: rinse cooked rice thoroughly with cold water, store it in a pottery vessel, cover tightly with a pottery lid to prevent gas escape, seal seams with bamboo shoots, and dry it over shallow water using firewood smoke. Each time eating, take it with Sesame seeds (Huma, 胡麻) and Pine nuts (Songzi, 松子). Start with cooked food, then cold food, gradually moving to raw food, gradually reducing quantity, then eating only sesame and pine nuts, gradually reducing them, and finally eating nothing, thereby achieving Bigu (Grain Avoidance, 辟谷), consuming only qi and no food. If there is wheat instead of rice, adjust the sequence: first mix and prepare, wash face, then eat meat first and vegetables later, use vegetables to swallow first and sesame/pine nuts later, gradually reduce intake, switch to cooked food; the sequence of cooked, cold, and no food remains the same. Reaching this level of practice attains the Middle Vehicle (Zhongcheng, 中乘). With persistent effort, one can ascend to the Highest Vehicle (Shangcheng, 上乘). People who set their minds on the Dao and are advised to practice Bigu often seek substitute meals out of impatience, leading to strange illnesses. This is due to neglecting the root for the branches.