南宗頓教最上大乘摩訶般若波羅蜜經六祖惠能大師於韶州大梵寺施法壇經 1.48

1.48

People of the world all say: 'Neng of the Southern School and Xiu of the Northern School,' not knowing the root reason. Chan Master Xiu resided and practiced at Yuquan Monastery in Dangyang County, Jiangling Prefecture of the Southern Capital, Jingzhou; Master Huineng resided and practiced at Caoxi Mountain, thirty-five li east of the city of Shaozhou. The Dharma is indeed one tradition, but the persons were in the south and north; therefore 'Southern' and 'Northern' were established. Why 'gradual' and 'sudden'? The Dharma is indeed of one kind, but seeing is slow or rapid: when seeing is slow, it is gradual; when seeing is rapid, it is sudden. The Dharma has neither gradual nor sudden, but people are sharp or dull; therefore it is called gradual and sudden.