"Chéngyǔ" are mostly derived from ancient literature, including the pre-Qin classics, poetry from all periods of Chinese history, and late imperial vernacular novels and short stories. A small number were constructed in the 19th and early 20th centuries from Western source materials. Among the early classical literature, the lyrical imagery from the "Shijing" and the detailed and vivid stories recorded in the "Zuozhuan" and the "Shiji" serve as particularly rich source materials for chéngyǔ. Since the "Shijing" poems consist of four-character lines, some chéngyǔ are direct quotes from the "Shijing". For example, ("wàn shòu wú jiāng", lit: "ten-thousand lifespan without bound"), a traditional expression to wish someone a long life (often appearing on bowls and other tableware), quotes the poem "Tian Bao" (, poem #166) in the Lesser Court Hymns section of the "Shijing". More commonly, however, chéngyǔ are created by succinctly paraphrasing or summarizing the original text, usually by selecting the most salient characters from the passage in question and inserting any necessary classical grammatical particles.