《阴阳应象论》云∶天以阳生阴长，地以阳杀阴藏。然岁以春为首，正，正也；寅，引
也。少阳之气始于泉下，引阴升而在天地人之上，即天之分，百谷草木皆甲坼于此时也。至
立夏少阴之火炽于太虚，则草木盛茂，垂枝布菜。乃阳之用，阴之体，此所谓天以阳生阴长
。经言岁半以前，天气主之，在乎升浮也。至秋而太阴之运，初自天而下逐，阴降而彻地，
则金振燥令，风厉霜飞，品物咸殒，其枝独存，若乎毫毛。至冬则少阴之气复伏于泉下，水
冰地坼，万类周密。阴之用，阳之体也，此所谓地以阳杀阴藏。经言岁半以后，地气主之，
在乎降沉也。至于春气温和，夏气暑热，秋气清凉，冬气冷洌，此则正气之序也。故曰∶履
端于始，序则不愆。升已而降，降已而升，如环无端，运化万物，其实一气也。
设或阴阳错综，胜复之变，自此而起。万物之中，人一也，呼吸升降，效象天地，
准绳阴阳。盖胃为水谷之海，饮食入胃，而精气先输脾归肺，上行春夏之令，以滋养周身，
乃清气为天者也；升已而下输膀胱，行秋冬之令，为传化糟粕，转味而出，乃浊阴为地者
也。若夫顺四时之气，起居有时，以避寒暑，饮食有节，及不暴喜怒，以颐神志，常欲四时
均平，而无偏胜则安。不然，损伤脾胃，真气下溜，或下泄而久不能升，是有秋冬而无春夏，
乃生长之用，陷于殒杀之气，而百病皆起；或久升而不降亦病焉。于此求之，则知履端之义
矣。
《阴阳应象论》中说：天依靠阳气使万物生长，依靠阴气使万物繁茂；地依靠阳气使万物肃杀，依靠阴气使万物闭藏。然而一年以春季为首，正（zhèng）意为端正；寅（yín）意为引动。少阳之气从地下泉水处开始发动，牵引阴气上升而处于天地人之上，这属于天的分野，此时百谷草木都破壳发芽。到了立夏时节，少阴之火在广阔天空中炽盛，于是草木茂盛，枝条下垂，叶片舒展。这是阳的作用，阴的形体，这就是所说的“天以阳生阴长”。经文说上半年由天气主导，在于升浮。到了秋季，太阴的运行，起初从天上向下追逐，阴气下降并通达大地，于是金气振作燥令，寒风凛冽，霜雪纷飞，各类事物都凋零死亡，只剩下树枝，如同毫毛一般。到了冬季，少阴之气重新潜伏在地下泉水之中，水结冰，土地开裂，万物严密闭藏。这是阴的作用，阳的形体，这就是所说的“地以阳杀阴藏”。经文说下半年由地气主导，在于降沉。至于春天气候温和，夏天气候暑热，秋天气候清凉，冬天气候寒冷刺骨，这是正气运行的次序。所以说：在年初开始时遵循正道，次序就不会有差错。升之后便降，降之后便升，像圆环一样没有尽头，运化万物，其实是一气罢了。
假如阴阳交错，胜复的变化，就从此产生。在万物之中，人是其中之一，呼吸升降，效法天地，以阴阳为准绳。大概胃是水谷的海，饮食进入胃中，精气先输送给脾，再归于肺，向上运行符合春夏的时令，来滋养全身，这就是清气成为天；升之后向下输送到膀胱，运行符合秋冬的时令，用来传导排泄糟粕，转化味道而出，这就是浊阴成为地。如果顺应四时的气候，起居有规律，以避开寒暑，饮食有节制，以及不突然发怒或喜悦，来养护神志，常常希望四时平衡，而没有偏胜，就能安康。不然的话，就会损伤脾胃，真气下溜，或者下泄且长久不能上升，这就只有秋冬而没有春夏，生长的作用陷入肃杀之气，从而百病皆起；或者长久上升而不下降也会生病。从这里探究，就知道遵循正道起始的含义了。
The *Yin Yang Ying Xiang Lun* (Treatise on Yin and Yang Corresponding to Images) states: Heaven utilizes Yang Qi (vital energy) to generate and Yin Qi to grow; Earth utilizes Yang Qi to wither and Yin Qi to store. However, the year begins in Spring; "Zheng" (Correct/Upright) means upright; "Yin" (Tiger/First Branch) means to lead. The Shao Yang Qi (Lesser Yang Vital Energy) begins to stir from below the springs, leading Yin Qi upward to reside above Heaven, Earth, and Humanity, which belongs to the realm of Heaven. At this time, all grains and trees split their shells and sprout. By the Start of Summer, the Fire of Shao Yin (Lesser Yin) blazes in the vast sky, causing vegetation to flourish luxuriantly, with branches drooping and leaves spreading. This is the function of Yang and the substance of Yin, which is what is meant by "Heaven utilizes Yang to generate and Yin to grow." The Classics state that during the first half of the year, Heavenly Qi dominates, focusing on ascending and floating. When Autumn arrives, the movement of Tai Yin (Greater Yin) initially descends from Heaven, chasing downward; Yin Qi sinks and penetrates to the Earth. Consequently, Metal Qi振作s the Dryness command, fierce winds blow, and frost flies, causing all things to perish, leaving only branches like hairs. In Winter, the Qi of Shao Yin lies dormant again beneath the springs; water freezes, the earth cracks, and all creatures are tightly sealed. This is the function of Yin and the substance of Yang, which is what is meant by "Earth utilizes Yang to wither and Yin to store." The Classics state that during the second half of the year, Earthly Qi dominates, focusing on descending and sinking. As for the climate: Spring is mild, Summer is hot, Autumn is cool, and Winter is biting cold. This is the sequence of Righteous Qi (Normal Vital Energy). Therefore it is said: Begin correctly at the start, and the order will not err. After ascending comes descending; after descending comes ascending, like a circle without end, transforming and transporting all things, yet essentially it is one Qi.
If Yin and Yang become entangled, changes of overcoming and counteracting arise from here. Among all things, humans are one; respiration and rising/falling imitate Heaven and Earth, using Yin and Yang as the standard. Generally speaking, the Stomach is the Sea of Water and Grain. When food and drink enter the Stomach, the Essence Qi is first transported by the Spleen and returned to the Lung, ascending upward according to the commands of Spring and Summer to nourish the whole body; this is Clear Qi becoming Heaven. After ascending, it descends downward to transport to the Bladder, operating according to the commands of Autumn and Winter to transmit and transform dregs, changing flavors and exiting; this is Turbid Yin becoming Earth. If one conforms to the Qi of the four seasons, has regular daily routines to avoid cold and heat, maintains dietary moderation, avoids sudden anger or joy to nurture the Spirit and Will, and constantly seeks balance among the four seasons without excess, then there will be peace. Otherwise, the Spleen and Stomach will be damaged, True Qi will flow downward, or leak out and fail to rise for a long time. This results in having only Autumn and Winter but no Spring and Summer, where the function of growth falls into the Qi of destruction, giving rise to myriad diseases; or if it rises for too long without descending, disease also occurs. Investigating this, one understands the meaning of beginning correctly.