A recurring debate within Zen and its Chinese Chan antecedent concerns the relationship between the suddenness of kensho or satori and the long, gradual training that surrounds it, sometimes summarized as sudden enlightenment against gradual cultivation. The Rinzai school, which places heavy emphasis on koan practice, intensive question and answer exchanges designed to exhaust the discursive mind and provoke a breakthrough, tends to foreground dramatic, datable kensho experiences as milestones a student and teacher can identify and confirm together.
The Soto school, associated with the teaching of Dogen and his practice of shikantaza, just sitting, has historically been more cautious about treating any single dramatic experience as the goal, emphasizing instead that enlightenment and practice are not two separate things, so that sitting meditation itself, done without seeking a special experience, is already an expression of Buddha nature rather than merely a means toward some later breakthrough. Both schools affirm kensho and satori as real and significant, and the difference is a matter of pedagogical emphasis and lineage style rather than a disagreement over whether such realization exists.