The Image of Music and Sound in Xunzi's 'On Music': A Study of Character, Cosmos, and the Cultivation of Rites and Music

Section 8: The "Eight Tones" and the "Eight Directions" — Cosmic Correspondence in Instrument Materials

The pre-Qin classification of the "Eight Tones" ($\text{bā yīn}$)—metal, stone, earth, leather, silk, wood, gourd, and bamboo—is not just a categorization of instrument materials but also embodies cosmological significance.

"Eight" ($\text{bā}$) was an important number in pre-Qin culture. The eight directions (East, West, South, North, Southeast, Southwest, Northeast, Northwest), the eight trigrams (Qian, Kun, Zhen, Xun, Kan, Li, Gen, Dui), and the eight tones (metal, stone, earth, leather, silk, wood, gourd, bamboo)—all use "eight" as the framework to encompass the entirety of existence.

The Rites of Zhou, Office of Music: Grand Master, records:

"All are spread forth by the Eight Tones: metal, stone, earth, leather, silk, wood, gourd, and bamboo."

The classification of the eight tones by material—what material an instrument is made of determines which "tone" it belongs to—is based on the philosophical presupposition that material determines character—instruments made of different materials possess different timbres, different qualities, and correspond to different cosmic elements.

Metal (Bell category): Derived from subterranean ores, refined by smelting, hard and heavy, sound is deep and substantial. The virtue of metal is "hardness" ($\text{gāng}$) and "substantiality" ($\text{shí}$).

Stone (Chime Stone category): Natural mineral, shaped without smelting, sound is crisp and sharp. The virtue of stone is "firmness" ($\text{jiān}$) and "clarity" ($\text{qīng}$).

Earth (Xun category): The essence of the soil, molded and fired, sound is low and deep. The virtue of earth is "richness" ($\text{hòu}$) and "primitiveness" ($\text{pǔ}$).

Leather (Drum category): Derived from animal hide, stretched over a frame, struck by a mallet to produce sound, sound is grand and deep. The virtue of leather is "grandness" ($\text{dà}$) and "movement" ($\text{dòng}$).

Silk (Qin/Se category): Derived from silkworms, used as strings on the qín and sè, plucked to produce sound, sound is gentle and beautiful. The virtue of silk is "softness" ($\text{róu}$) and "beauty" ($\text{měi}$).

Wood (Zhù/Yǔ category): From trees, used to make square or tiger-shaped percussion instruments, sound produced by striking. The virtue of wood is "simplicity" ($\text{pǔ}$) and "straightness" ($\text{zhí}$).

Gourd (Sheng/Yu category): The fruit of the gourd, used as the chamber for the shēng, with bamboo reeds inserted, sound produced by blowing. The virtue of gourd is "harmony" ($\text{hé}$) and "roundness" ($\text{yuán}$).

Bamboo (Xiao, Guan, Yue, Chi category): Grows upright with nodes, hollowed out into tubes, sound produced by blowing. The virtue of bamboo is "straightness" ($\text{zhí}$) and "brightness" ($\text{liàng}$).

The eight materials—metal, stone, earth, leather, silk, wood, gourd, bamboo—cover the main material types in the natural world: minerals (metal, stone), soil (earth), animal products (leather, silk), and plant products (wood, gourd, bamboo). Instruments made from these eight materials produce eight different qualities of sound, forming a complete sonic universe.

This is the cosmological foundation of "The Imagery of Sound and Music"—instruments are made from natural materials, and their sonic qualities are determined by the natural qualities of those materials; therefore, the sounds of the instruments naturally correspond to the elements of Heaven and Earth ($\text{tiān dì}$), the myriad things. This is not an arbitrary parallel construction but a natural affinity arising from the inherent connection between things.