In Korean Seon, koans—known as *gong’an* and often engaged through the key phrase or *hwadu*—function as central instruments for awakening rather than as intellectual riddles. The practitioner takes up a brief, pointed question or phrase, such as “What is this?”, and sustains an intense, living inquiry into it. This is not a matter of solving a problem conceptually, but of allowing the question to permeate awareness so thoroughly that ordinary patterns of thought are gradually worn out. Through this process, the practice generates what the tradition calls “great doubt,” a profound existential questioning that unsettles habitual certainties. When discursive thinking is exhausted in this way, the possibility opens for a sudden breakthrough experience, a direct realization of one’s original nature or Buddha-nature.

This koan-centered discipline, often referred to as *ganhwa Seon* (“observing the critical phrase”), is not confined to formal meditation periods. The *hwadu* is carried into walking, working, eating, and all the ordinary activities of daily life, so that the mind is continually turned back toward its source. In this sense, koan practice becomes a thread that unifies the whole of existence, integrating contemplative inquiry with every moment. By confronting paradoxical or seemingly nonsensical statements that defy logical resolution, practitioners are gently but firmly pushed beyond dualistic habits—beyond notions of right and wrong, subject and object, existence and nonexistence. What emerges is not a clever answer, but a non-dual awareness that cannot be captured in words.

Koans also serve an important pedagogical and relational function within the Seon community. Masters employ them to gauge the depth and authenticity of a student’s realization, attending closely to how the student responds—in speech, gesture, or silence—as an expression of insight. According to the student’s maturity, a teacher may assign, change, or withhold particular koans, using them as precise tools to guide practice. In this way, koans preserve and transmit the living style and spirit of the Seon lineage, linking present practitioners with the awakening of past masters and sustaining the continuity of genuine understanding across generations.