郑世子曰∶按阳律生阴，下生；阴律生阳，上生。阴阳之分，古有二说∶其一说者，十二
律吕，各照方位，在子午以东属阳，子午以西属阴。是故子黄钟，一阳复卦；丑大吕，二阳临
卦；寅太簇，三阳泰卦；卯夹钟，四阳大壮卦；辰姑洗，五阳 卦；巳仲吕，六阳乾卦；午蕤宾，
一阴 卦；未林钟，二阴遁卦；申夷则，三阴否卦；酉南吕，四阴观卦；戌无射，五阴剥卦；亥
应钟，六阴坤卦。干为老阳，故仲吕亢极不生；坤为老阴，故应钟极短为终。大吕、夹钟、仲
吕，三吕以阴居阳，故皆属阳；蕤宾、夷则、无射，三律以阳居阴，故皆属阴。凡律清者皆上
生，浊者皆下生。此一说也。又一说云∶六律数奇属阳，六吕数偶属阴。是故子黄钟，干之
初九；寅太簇，干之九二；辰姑洗，干之九三；午蕤宾，干之九四；申夷则，干之九五；戌无射，
干之上九。此六律数奇，各居本位属阳也。丑林钟，坤之初六；卯南吕，坤之六二；巳应钟，
坤之六三；未大吕，坤之六四；酉夹钟，坤之六五；亥仲吕，坤之上六。此六吕数偶，各居对
冲属阴也。居本位者皆下生，居对冲者皆上生。此又一说也。以上二说，自汉至今，是非
不决。盖太史公律书兼有此二种，故汉晋梁唐争执不定，而朱子经世大训，所解甚明。盖
以一岁言，则冬至以后属阳，夏至以后属阴，以一日言，则子时以后属阳，午时以后属阴，所
谓大阴阳也。子阳丑阴、寅阳卯阴之类，所谓小阴阳也。律吕阳下生阴，阴上生阳，盖指其
大者耳。凡阴吕居阳方，即皆属阳；阳律居阴方，即皆属阴。故别论小阴阳，乃变例也；其
余诸律，则只论大阴阳，乃正例也。朱子此论，非蔡元定所及。一曰∶律左吕右，其行不同，
如筮法然。故黄钟至仲吕，子至巳阳升阴退，故律生吕言下生，吕生律言上生；蕤宾至应
钟，午至亥阴升阳退，故律生吕言上生，吕生律言下生。至午而变，故蕤宾重上生。若论捷
法，不出乾坤六阳六阴者为便。子寅辰午申戌，黄太姑蕤夷无，一如干之左旋，是之谓律而
下生；未巳卯丑亥酉，林仲夹大应南，又如坤之右转，是之谓吕而上生。此郑玄筮法之言，得之太玄也。
郑世子说：按照阳律产生阴律，是从下方产生；阴律产生阳律，是从上方产生。关于阴阳的划分，古代有两种说法。第一种说法认为，十二律吕各自对应方位，在子午线以东属于阳，子午线以西属于阴。因此，子位的黄钟，对应一阳复卦；丑位的大吕，对应二阳临卦；寅位的太簇，对应三阳泰卦；卯位的夹钟，对应四阳大壮卦；辰位的姑洗，对应五阳卦（注：原文此处缺字，通常指夬卦）；巳位的仲吕，对应六阳乾卦；午位的蕤宾，对应一阴姤卦（注：原文此处缺字，通常指姤卦）；未位的林钟，对应二阴遁卦（注：原文此处缺字，通常指遯卦）；申位的夷则，对应三阴否卦；酉位的南吕，对应四阴观卦；戌位的无射，对应五阴剥卦；亥位的应钟，对应六阴坤卦。乾代表老阳，所以仲吕亢极而不生；坤代表老阴，所以应钟极短作为终结。大吕、夹钟、仲吕这三个吕以阴居阳位，所以都归属于阳；蕤宾、夷则、无射这三个律以阳居阴位，所以都归属于阴。凡是清亮的律都向上生，浑浊的都向下生。这是第一种说法。
另一种说法认为：六律数字为奇数属于阳，六吕数字为偶数属于阴。因此，子位的黄钟，对应乾卦的初九；寅位的太簇，对应乾卦的九二；辰位的姑洗，对应乾卦的九三；午位的蕤宾，对应乾卦的九四；申位的夷则，对应乾卦的九五；戌位的无射，对应乾卦的上九。这六个律数字为奇数，各自处于本位属于阳。丑位的林钟，对应坤卦的初六；卯位的南吕，对应坤卦的六二；巳位的应钟，对应坤卦的六三；未位的大吕，对应坤卦的六四；酉位的夹钟，对应坤卦的六五；亥位的仲吕，对应坤卦的上六。这六个吕数字为偶数，各自处于对冲位置属于阴。处于本位的都向下生，处于对冲位置的都向上生。这是第二种说法。以上两种说法，从汉代到现在，是非未决。因为司马迁的《律书》同时包含了这两种观点，所以汉晋梁唐时期争论不休，而朱熹在《经世大训》中的解释非常明确。大概以一年而言，冬至以后属于阳，夏至以后属于阴；以一天而言，子时以后属于阳，午时以后属于阴，这叫做“大阴阳”。子阳丑阴、寅阳卯阴之类，叫做“小阴阳”。律吕阳下生阴，阴上生阳，大概是指其中的大体规律罢了。凡是阴吕居住在阳方，就都归属于阳；阳律居住在阴方，就都归属于阴。所以另外讨论小阴阳，是变通的特例；其余各律，只讨论大阴阳，是正例。朱熹的这个论点，不是蔡元定所能达到的。有一种说法认为：律在左，吕在右，它们的运行不同，就像占卜的方法一样。所以从黄钟到仲吕，从子到巳，阳气上升阴气退却，所以律生吕时说“下生”，吕生律时说“上生”；从蕤宾到应钟，从午到亥，阴气上升阳气退却，所以律生吕时说“上生”，吕生律时说“下生”。到了午位发生变化，所以蕤宾重新“上生”。如果论及简便的方法，不出乾坤六阳六阴的范围最为便利。子、寅、辰、午、申、戌，黄钟、太簇、姑洗、蕤宾、夷则、无射，完全像乾卦的左旋，这就叫作“律而下生”；未、巳、卯、丑、亥、酉，林钟、仲吕、夹钟、大吕、应钟、南吕，又像坤卦的右转，这就叫作“吕而上生”。这是郑玄关于占卜方法的言论，得自于扬雄的《太玄》。
The Prince of Zheng stated: According to the principle, Yang Lü (Yang pitch-pipes) generating Yin Lü (Yin pitch-pipes) occurs from below; Yin Lü generating Yang Lü occurs from above. Regarding the division of Yin and Yang, there have been two ancient theories. The first theory posits that the Twelve Lü (Twelve Pitch-pipes) correspond to specific directions: those east of the Zi-Wu line belong to Yang, and those west of it belong to Yin. Thus, Huangzhong at Zi corresponds to the Fu Hexagram (Return); Dalu at Chou corresponds to the Lin Hexagram (Approach); Taicu at Yin corresponds to the Tai Hexagram (Peace); Jiazhong at Mao corresponds to the Da Zhuang Hexagram (Great Power); Guxian at Chen corresponds to the Guai Hexagram (Breakthrough); Zhonglü at Si corresponds to the Qian Hexagram (The Creative); Ruibin at Wu corresponds to the Gou Hexagram (Coming to Meet); Linzhong at Wei corresponds to the Dun Hexagram (Retreat); Yize at Shen corresponds to the Pi Hexagram (Standstill); Nanlü at You corresponds to the Guan Hexagram (Contemplation); Wuyi at Xu corresponds to the Bo Hexagram (Splitting Apart); Yingzhong at Hai corresponds to the Kun Hexagram (The Receptive). Qian represents Old Yang, therefore Zhonglü is extreme and does not generate; Kun represents Old Yin, therefore Yingzhong is extremely short and serves as the end. Dalu, Jiazhong, and Zhonglü are three Lü positioned in Yang places, thus they all belong to Yang; Ruibin, Yize, and Wuyi are three Lü positioned in Yin places, thus they all belong to Yin. All clear pitch-pipes generate upwards, and all turbid ones generate downwards. This is the first theory.
Another theory states: The Six Lü (Yang pitch-pipes) with odd numbers belong to Yang, and the Six Lü (Yin pitch-pipes) with even numbers belong to Yin. Therefore, Huangzhong at Zi corresponds to the Initial Nine of Qian; Taicu at Yin corresponds to the Second Nine of Qian; Guxian at Chen corresponds to the Third Nine of Qian; Ruibin at Wu corresponds to the Fourth Nine of Qian; Yize at Shen corresponds to the Fifth Nine of Qian; Wuyi at Xu corresponds to the Top Nine of Qian. These six Lü have odd numbers and reside in their original positions, belonging to Yang. Linzhong at Chou corresponds to the Initial Six of Kun; Nanlü at Mao corresponds to the Second Six of Kun; Yingzhong at Si corresponds to the Third Six of Kun; Dalu at Wei corresponds to the Fourth Six of Kun; Jiazhong at You corresponds to the Fifth Six of Kun; Zhonglü at Hai corresponds to the Top Six of Kun. These six Lü have even numbers and reside in opposing positions, belonging to Yin. Those in original positions generate downwards, while those in opposing positions generate upwards. This is the second theory. Since the Han Dynasty until now, the validity of these two theories remains undetermined. Sima Qian's *Book of Music* includes both views, leading to disputes during the Han, Jin, Liang, and Tang dynasties. However, Zhu Xi's explanation in *Jingshi Daxun* is very clear. Generally speaking, regarding a year, the period after Winter Solstice belongs to Yang, and the period after Summer Solstice belongs to Yin; regarding a day, the time after Zi hour belongs to Yang, and the time after Wu hour belongs to Yin. This is called "Great Yin and Yang." Examples like Zi-Yang/Chou-Yin, Yin-Yang/Mao-Yin are called "Small Yin and Yang." The generation of Yin from Yang Lü and Yang from Yin Lü refers to the general principle. Whenever Yin Lü resides in a Yang position, it belongs to Yang; whenever Yang Lü resides in a Yin position, it belongs to Yin. Therefore, discussing Small Yin and Yang is a special variation; for other Lü, only Great Yin and Yang are discussed, which is the standard rule. Zhu Xi's argument surpasses that of Cai Yuanding. One view holds: Lü on the left, Lü on the right, their movements differ, similar to divination methods. Thus, from Huangzhong to Zhonglü, from Zi to Si, Yang rises and Yin retreats; hence, when Lü generates Lü, it is called "generating downwards," and when Lü generates Lü, it is called "generating upwards"; from Ruibin to Yingzhong, from Wu to Hai, Yin rises and Yang retreats; hence, when Lü generates Lü, it is called "generating upwards," and when Lü generates Lü, it is called "generating downwards." Change occurs at Wu, so Ruibin re-generates upwards. If discussing a convenient method, it does not go beyond the Six Yang and Six Yin of Qian and Kun. Zi, Yin, Chen, Wu, Shen, Xu; Huang, Tai, Gu, Rui, Yi, Wu, exactly like the counter-clockwise rotation of Qian, this is called "Lü generating downwards"; Wei, Si, Mao, Chou, Hai, You; Lin, Zhong, Jia, Da, Ying, Nan, exactly like the clockwise rotation of Kun, this is called "Lü generating upwards." This is Xuan Zheng's statement on divination methods, derived from Yang Xiong's *Taixuan*.