郑世子曰∶八音之内，当以竹音为首；竹音之内，当以律管为首。律管之为器，吹之以
候气，奏之以和声。舜典所谓律和声，月令所谓律中某之类，皆指律管而言。是知管即律，
律即管，一物而二名也。形而上者谓之道，形而下者谓之器；律者其道也，管者其器也。书
曰下管 鼓，诗曰磬管将将， 管声，礼曰下管新宫，下而管象，与夫孤竹、孙竹、阴竹之
管，皆是物也，然则先王雅乐，何尝不用管哉？近代雅乐废之何也？盖由前儒不识管者，谓
管如HT 而小，并两而吹。疏引广雅云∶管长尺围寸，八孔无底，或云六孔。此汉大予乐官之
双管，非古所谓管也。今按八孔双管，声如头管，俚俗有之，不入雅乐，旧说非是。后儒不
识管者，谓管除HT 子外，长六寸余。此系教坊俗乐之头管，亦非所谓管也。所谓管者无孔，
凡有孔者非也。惟管端开豁口，壮如洞箫，形似洞门，俗名洞箫者以此。礼运载孔子之言
曰∶五声六律十二管，还相为宫。据此明言管有十二，而世儒止知双管头管何哉？（ 音桃。
音讳。HT 音叫。）
按律吕精义，管制有三，即前纵黍斜黍横黍之谓。根据纵黍尺，黄钟管长八寸一分，外径
四分零五毫，内径二分八厘六亳，吹口广一分四厘三亳。斜黍尺长九寸。横黍尺长一尺。
三制围径之数，及十二管详数，具载本书，兹不备录。
郑世子说：在八音（金、石、丝、竹、匏、土、革、木）之中，应当以竹类乐器为首；在竹类乐器之中，应当以律管为首。律管作为一种器具，吹奏它是为了候察节气之气，演奏它是为了调和声律。《尚书·舜典》中说的“律和声”，《礼记·月令》中说的“律中某律”之类，都是指律管而言。由此可知，管就是律，律就是管，是同一件东西的两个名称。形而上的叫做道，形而下的叫做器；律属于道的范畴，管属于器的范畴。《尚书》中说“下管鼛鼓”，《诗经》中说“磬管将将”，“管声”和谐，《礼记》中说“下管新宫”、“下而管象”，以及所谓孤竹管、孙竹管、阴竹管的管子，都是这一类器物，那么先王的雅乐，何曾不用过管呢？近代为何废弃了它呢？大概是由于前代的儒者不认识真正的管，认为管像篪（chí，一种竹制横吹乐器）但较小，是将两支合在一起吹奏的。疏证引用《广雅》说：“管长一尺，围一寸，有八个孔且底部不通，也有人说有六个孔。”这是汉代大予乐官所用的双管，并非古代所说的管。现在考察那八孔双管，声音如同头管（一种民间乐器），在民间俗乐中有使用，但不进入雅乐体系，所以旧的说法是不对的。后代的儒者也不认识真正的管，认为管除了插簧片的部分外，长度只有六寸多。这属于教坊俗乐中的头管，也不是所谓的管。真正的管是没有孔的，凡是带孔的都不是。只有在管的一端开豁口，形状像洞箫一样，外形似洞门，这就是俗名洞箫的原因。《礼记》记载孔子说的话：“五声六律十二管，还相为宫。”据此明确说明管有十二支，而世间的儒者只知道双管和头管，这是为什么呢？（“篪”音桃，“鼛”音讳，“簧”音叫。）
根据《律吕精义》，管的制式有三种，即前面提到的纵黍尺、斜黍尺、横黍尺的说法。依据纵黍尺的标准，黄钟管的长度为八寸一分，外径四分零五毫，内径二分八厘六毫，吹口宽度一分四厘三毫。斜黍尺的长度为九寸。横黍尺的长度为一尺。这三种制式的围径数值，以及十二支管的详细数据，都详细记载在本书中，这里不再全部罗列。
The Prince of Zheng stated: Among the Eight Tones (the eight categories of ancient Chinese musical instruments classified by material: metal, stone, silk, bamboo, gourd, clay, leather, and wood), the bamboo category should be regarded as primary; among the bamboo instruments, the Lü Guan (Lü tube) should be considered paramount. As an instrument, the Lü Guan is blown to observe the Qi (vital energy/atmospheric conditions) of the seasons and played to harmonize the sounds. The phrases "Lü harmonizes the sounds" in the *Book of Documents* (*Shangshu*) and "Lü corresponds to [a certain month]" in the *Monthly Ordinances* (*Yueling*) all refer to the Lü Guan. Thus, it is known that the Guan is the Lü, and the Lü is the Guan; they are two names for a single object. That which is above form is called Dao (the Way); that which is below form is called Qi (vessel/instrument). The Lü belongs to the realm of Dao, while the Guan belongs to the realm of Qi. The *Book of Documents* states "Guan plays below, accompanied by large drums," the *Classic of Poetry* (*Shijing*) says "The qing and guan sound resonant," and the *Book of Rites* (*Liji*) mentions "Guan plays below, Xin Gong," "Guan plays below, Xiang," as well as tubes made from Gu Zhu (single-stalk bamboo), Sun Zhu (branch bamboo), and Yin Zhu (shade bamboo). All these are such objects. Then why did the ancient kings' elegant music ever fail to use the Guan? Why was it abandoned in recent times? This is likely because earlier scholars did not recognize the true Guan, believing it to be similar to a Chi (a bamboo flute with a membrane hole) but smaller, and consisting of two tubes joined together for blowing. Commentaries cite the *Guangya*, stating: "The Guan is one chi long, one cun in circumference, has eight holes and no bottom, or some say six holes." This refers to the double Guan used by the Da Yu Music Officials of the Han Dynasty, not the Guan referred to in antiquity. Upon examination, the eight-holed double Guan sounds like a Tou Guan (head pipe, a folk instrument) and exists in folk traditions, but does not belong to elegant music; thus, the old theory is incorrect. Later scholars also failed to recognize the true Guan, claiming that apart from the reed section, the Guan is only slightly over six cun long. This pertains to the Tou Guan used in Jiao Fang (Imperial Academy) folk music, which is also not the so-called Guan. The true Guan has no holes; anything with holes is not it. Only the end of the Guan is open, resembling a Dong Xiao (hole flute) in shape, looking like a cave entrance; this is why it is commonly named Dong Xiao. The *Book of Rites* records Confucius's words: "Five tones, six Lü, twelve Guan, return to each other to establish the Gong tone." This explicitly states there are twelve Guan, yet contemporary scholars only know of the double Guan and the Tou Guan. Why is this? (Note: 'Chi' is pronounced Tao; 'Gao' is pronounced Hui; 'Huang' is pronounced Jiao.)
According to the *Lü Lü Jing Yi* (Essence and Meaning of Pitch-Pipes and Tone-Standards), there are three systems of Guan construction, referring to the previously mentioned Zong Shu (vertical millet grain), Xie Shu (slanted millet grain), and Heng Shu (horizontal millet grain) standards. Based on the Zong Shu Chi standard, the Huang Zhong Guan is 8.1 cun long, with an outer diameter of 4.05 hao, an inner diameter of 2.86 li, and a blowing mouth width of 1.43 li. The Xie Shu Chi length is 9 cun. The Heng Shu Chi length is 1 chi. The circumferences and diameters of these three systems, along with the detailed measurements of the twelve Guan, are fully recorded in this book and are not listed here in full.