The quatrain is one of the important styles of ancient Chinese poetry. According to the number of characters, they can be divided into quatrains with five-character lines and quatrains with seven-character lines. A quatrain with four five-character lines has 20 characters, while a quatrain with four seven-character lines contains 28 characters. In terms of rules and forms, those that conform to the rules and forms are called “rules-based quatrains” while those that do not are termed “ancient quatrains.” The five-character quatrain originated from the yuefu poetry and folk songs of the Han Dynasty, while those with seven-character lines originated from the ballads of the Wei and Jin dynasties. During the Northern and Southern Dynasties, the vigorous growth of yuefu folk songs encouraged the literati to write large numbers of five-character poetry imitating the yuefu style, which promoted the development of these quatrains. In addition, the quatrains with five- and seven-character lines created in the Northern and Southern Dynasties began to stress tonal and rhythmic patterns. By the Tang Dynasty, rules-based poetry gradually became well-defined, and ancient quatrains and rules-based quatrains with five- and seven-character lines became the mainstream poetic styles, and a large number of famous poets and masterpieces emerged. As the quatrains are short and almost end the moment they begin, extra attention is required for their layout. Poets not only place emphasis on the completeness of the meaning, on freshness and naturalness, but also on the underlying nuances of words and rhymes.

Quatrains with five- and seven-character lines probably came from short ancient poems with five- and seven-character lines. Short ancient poems with five-character lines are found among the poems of the Han and Wei dynasties; and there are countless numbers of them. The quatrains of the Tang Dynasty were actually developed out of these. (Hu Yinglin: An In-depth Exploration of Poetry)

Quatrains should be written in a subtle and pleasing manner, removing complexity and pursuing simplicity so that when the text reaches its end, the charm continues to resonate. (Yang Zai: The Writing Know-how of Great Poets)