And scientists have already pronounced (prevacally?) that there is no birth and no death. Nothing is created, nothing is lost. There is only transformation. So, transformation is possible, is real. And birth and death are not real. What you call birth and death, are only transformation. ... When you look at the blue sky, you don't see your cloud anymore. You think your cloud has died. But in fact, your cloud continues always in the form of rain and so on. So, birth and death are seen only on the surface. If you go down, deep down, there is no birth and no death. There is only continuation. And when you touch the continuation, the nature of no birth and no death, you are no longer afraid of dying.
And not only the Buddhists speak of no birth and no death but science also speaks of no birth and no death. They can exchange their findings. It is very interesting. This is an invitation for us to live our life more deeply so that we can touch our true nature of no birth and no death. And Thay's answer, I know, is only an invitation to practice. We have to live our life more mindfully with concentration so that we can be in touch deeply with what is happening. And then we have a chance to touch the true nature of reality, no birth and no death. And that is described in Buddhism with the term of Nirvana. Nirvana is no birth and no death.
And in Christianity, you may call it the ultimate, God. God is our true nature of no birth and no death. And we don't have to go and find God. God is our true nature. It's like a wave. A wave believes that she is subjected to birth and death. And every time she comes up and begins to go down, she is afraid of dying. A wave is afraid of dying. But if the wave realizes that she is water, she is no longer afraid. Before going up, she is water. Going down, she is water. And after going down, she continues to be water. There is no death.
So, it is very important that the wave do some meditation and realizes that she is wave but she is at the same time water. And when she knows she is water, she is no longer afraid of dying. She feels wonderful going up, she feels wonderful going down. She is free from fear. And our cloud is also like that. They are not afraid of dying. They know that if they are not a cloud, they can be something else, equally beautiful like the rain or the snow.
So, the wave does not go and look for water. She doesn't have to go and search for water because she is water in the here and the now. The same thing is true with God. We don't have to look for God. We are God. God is our true nature. You don't have to go and look for nirvana. Nirvana is our ground. That is the teaching of the Buddha. And a number of us have been able to realize that. We enjoy the present moment. We know that it is impossible for us to die.
For everything (including humans) in the phenomenal world, there is only continuation by changing forms. Nothing can be created and nothing can be destroyed. And the total sum of the energy and mass is conserved in ecosystem according to the law of conservation of energy and mass (E=mc2). Therefore, birth and death are nothing but notions created by humans. The truth is there is no birth and no death. There is only continuation. Everything will continue in different forms eternally.
Thay understands this ultimate truth deeply but explained about life after death based on interbeing, or emptiness by using the conventional truth (by using the notion of birth and death). In the phenomenal world (outside world in space and time), the pairs of opposites are empty of separate existence and are interdependent co-arising. In other words, they are two sides of the same coin. So, if death is there, birth is there at the same time. It is like that the death of the cloud is the birth of the rain. Both of the cloud and the rain is water. They just continue in different form. Water never dies and never be born. Water is always water.
And the same thing can be said to humans also. Humans are always the whole cosmos because we are made of the whole cosmos such as water, air, earth and sunshine. If we understand this ultimate truth of no birth and no death, we will be able to throw away all notions and attain full enlightenment. Meanwhile, in the noumenal world (inside world without space and time), nothing can exist because there is no space and time. And only awareness (Buddha nature or Divine nature) can live in both worlds at the same time because awareness transcends space and time.
Thích Nhất Hạnh