The Chan master Dahui Zonggao (Ta-hui Tsung-kao) (1089-1163) perfected the koan technique. One of his first teachers reportedly interviewed him on the koans in the collection now known as the Blue Cliff Record, but he did so by not speaking a word and thereby forcing Dahui to work them out for himself.
Dahui also experimented with the Caodong teachings, but early on began to question the straitlaced, quietistic approach of that house. He finally was directed to the teacher Yuanwu Keqin (Yuan-wu K'o-ch'in) of the Linji school, beginning the association that would move him to the forefront of the struggle to save Chan via the koan.
Dahui experienced his first enlightenment hearing these words of Yuanwu:
A monk: "From whence came all the buddhas?"
Yuanwu: "Warm breezes come from the South, but in the palace
there's a cold draught."