Zenrin-kushū

Zenrin-kushū is a collection of writings used in the Rinzai school of Zen. Initially it was a compilation of Zen writings by Tōyō Eichō a disciple of Kanzan Egen of the Myōshin-ji line of Rinzai school in Kyoto, Japan. Tōyō's anthology consisted of 5,000 writings compiled from writings of various traditions, such as Confucianism, Taoism and Zen, and the poetry of Tang and Song China.

Expanded version

This was known as the Ku Zōshi, and circulated in manuscript form until the 17th century, when Ijūshi published for the first time in 1688 an expanded version of the book, titled Zenrin-kushū. It is known that at least since the time of Hakuin Ekaku the Zenrin-kushū has been used as part of the kōan practice, as the jakugo or capping verses — responses by students to problems given to them by their teachers.