The goal of koan practice in Rinzai Zen is to reach sudden awakening, also known as kensho or satori. This is a state of profound understanding and insight into the true nature of reality, beyond conceptual thinking and dualistic distinctions. It is considered the ultimate goal of Zen practice.

Koans are short, paradoxical statements or questions that are used as a tool for meditation and contemplation in Rinzai Zen. They are meant to disrupt the logical and rational mind, and to challenge the practitioner to go beyond their usual ways of thinking. Koans often have no logical answer, and therefore cannot be solved through intellectual reasoning.

The purpose of koan practice is to break through the limitations of the ego and the conditioned mind, and to experience a direct realization of one's true nature. This is achieved through a process of intense questioning and introspection, guided by a teacher who has already experienced kensho themselves.

In Rinzai Zen, koans are seen as a means to an end, rather than an end in themselves. They are used as a means to shake the practitioner out of their habitual patterns of thinking and to open them up to the possibility of sudden awakening. This is why koans are often described as "skillful means" or "medicine for the mind" in Rinzai Zen.

The process of koan practice can be intense and challenging, as it requires the practitioner to let go of their attachment to their own thoughts and beliefs. It also involves facing the doubts and fears that arise when the mind is pushed beyond its usual limits. However, through this process, the practitioner can come to a deeper understanding of the nature of reality and their own true self.

Ultimately, the goal of koan practice in Rinzai Zen is to awaken to the true nature of reality and to live in a state of constant awareness and presence. This is not a goal that can be achieved through intellectual understanding alone, but rather through a direct experience of kensho. Through koan practice, practitioners can cultivate the ability to access this state of sudden awakening at any time, and to live in harmony with the world around them.