In Rinzai Zen, the concept of sudden awakening is closely tied to the concept of impermanence. This is because both concepts emphasize the idea that everything in life is constantly changing and nothing is permanent.

Sudden awakening, also known as kensho, is a central practice in Rinzai Zen. It involves using koans, or paradoxical statements or questions, to help break through the dualistic thinking of the mind and reach a state of sudden enlightenment. This sudden awakening is said to be a direct experience of one's true nature or Buddha nature, which is not bound by the limitations of the ego or the concept of self.

Impermanence, on the other hand, refers to the Buddhist understanding that all things in life are constantly changing and nothing remains the same. This includes our thoughts, emotions, and physical experiences. In Rinzai Zen, impermanence is seen as a fundamental truth of existence and is often used as a tool for contemplation and meditation.

So how do these two concepts tie together? Sudden awakening is seen as a sudden realization of the impermanent nature of all things. When one experiences kensho, they are said to see the world in a completely different way, free from the limitations of the ego and the illusion of permanence. This sudden shift in perspective allows one to see the impermanence of all things in a more direct and profound way.

Furthermore, the practice of koans in Rinzai Zen is also rooted in the understanding of impermanence. Koans are meant to be contemplated and meditated on, not solved or answered. This is because the answer to a koan is not a fixed or permanent truth, but rather a constantly evolving understanding of reality. The koan itself may have different meanings and interpretations depending on the individual and their state of mind. This reflects the impermanence of all things, including our own perceptions and understanding.

In summary, the concept of sudden awakening in Rinzai Zen is closely tied to the concept of impermanence. Both emphasize the idea that everything in life is constantly changing and nothing is permanent. Through the practice of sudden awakening and the contemplation of impermanence, one can gain a deeper understanding of the true nature of reality and break free from the limitations of the ego and the illusion of permanence.