In Linji’s teaching, the katsu shout is a direct, non-conceptual intervention that cuts straight through the tangle of discursive thought. Rather than functioning as a mystical formula or symbolic code, it operates as an abrupt interruption of the mind’s habitual grasping at words, doctrines, and explanations. This sudden shock is meant to sever reliance on intellectual understanding and dualistic thinking, leaving the practitioner momentarily without a foothold. In that gap, where conceptualization falters, the possibility of seeing one’s own inherent Buddha-nature becomes vivid and immediate.

The shout thus serves as a wordless Dharma, a complete teaching enacted rather than described. It does not point to some distant attainment but embodies the very movement of awakening itself, revealing what some traditions call the “true person of no rank,” the original mind prior to all labels and roles. In this sense, katsu is a non-verbal method that both expresses and communicates awakened nature, not through explanation but through a jolt that demands direct, present-moment awareness. It is a challenge to complacency, shaking students out of spiritual stagnation and undermining subtle clinging to methods, teachers, and even the idea of enlightenment.

At the same time, the shout functions as a test and a mirror, exposing the student’s actual level of understanding and responsiveness. By responding to katsu, or failing to respond, the practitioner reveals whether practice remains entangled in concepts or has begun to move from the same free, uncontrived source that the master demonstrates. In this way, the shout is both a skillful means to break attachments and a demonstration of the master’s own freedom from conventional constraints. It is not the sound itself that is important, but the living, ungraspable reality to which it points in an instant, beyond all formulations and practices.