碧巌録
Yuanwu's successor, Dahui Zonggao (1089–1163), wrote many letters to lay students teaching the practice of concentrating on koans during meditation, but Dahui did not explain and analyze koans. Oral tradition holds that Dahui noticed students engaged in too much intellectual discourse on koans, and then burned the wooden blocks used to print the "Blue Cliff Record" to "rescue disciples from delusion".