There is a teaching called the teaching on the Three Seals, Three Dharma Seals. [Thay writes on the board: Impermanence.]

The teaching of impermanence is not to discourage you, to make you worry. This teaching is for you to learn to look at things and touch their nature of impermanence. You are impermanent, your beloved one is impermanent, the cloud is impermanent, the flower is also impermanent. And impermanence makes it possible for life to go on. It is very important.

For a good practitioner, she has to maintain the insight of impermanence alive. She does not just say, "Yes, I agree with you that things are impermanent." That is not enough. Because even if she agrees, accepts with her intellect that things are impermanent, she still behaves like things are permanent.

Look at yourself. You are thinking of yourself as permanent. But the fact is not that. You have changed a lot. Look at yourself when you were a baby and yourself now. What kind of difference? What difference? "How different do I look now from the time I was a baby?" You are no longer him or her. And you are going to look very differently ten years from now.

And yet, impermanence is a fact in your body, is a reality in your body, your consciousness, and your feelings. But you still continue to think of you as a permanent entity. That is what we call ignorance. You think of you as permanent. You think of him or her as permanent, while you agree intellectually that everything is impermanent. So the concept of impermanence does not help.

The Buddha does not want you to accept the fact that things are impermanent. He wants more. He wants you to live your daily life in such a way that the insight of impermanence is always there within yourself. That is why we need the practice of samādhi. Samādhi means concentration. And that concentration should be maintained.

[Thay writes on the board: 等持.]

Samādhi, in Chinese, is translated by děng chí. Děng means the same level, always like that. You don't go down like this. And chí means to maintain. Děng chí. You maintain that awareness, that insight alive for a long time.

So for a good practitioner, the insight of impermanence should be maintained day and night. When she touches herself, she knows that she is impermanent. When she looks at another person, she knows that he is impermanent. Looking at her teacher, she knows that her teacher is impermanent. Looking at her younger brother, she knows that her younger brother is impermanent. Everything is impermanent.

And that insight of impermanence helps you not to do things that you regret later. Because we do things, we behave as if things are not impermanent. That is why it is the samādhi of impermanence that we need, not a concept of impermanence. That insight should be kept alive every moment of your daily life.