Life is always with death at the same time. Not only before. And it can not be separated with death. Where there is life, there is death. And where there is death, there is life.
And this needs a little bit of meditation. In Buddhism, we speak of 'interbeing'. It means that you can not be by yourself alone. You have to inter-be with the other side. It's like the left and the right. If the right is not there, the left can not be. If the left is not there, the right can not be. It's not possible to take the left away from the right. It's not possible to take the right away from the left. ... The right and the left, they want to be together. Because without the other, you can not be. It's very clear like the above and the below. The above can not be there if there is no below. And that is what in Buddhism we call 'interbeing'. They have to be there at the same time.
So, when God said, "Let the light be", and the light said, "Well, I have to wait, my God, I have to wait." "But what are you waiting?" "I am waiting for darkness to manifest together. Because light and darkness, they inter-are." And God said, "Darkness is already there." And the light said, "In that case, I am already there."
So, that is true with good and evil, before and after, here and there, you and I. I can not be there without you. The lotus flower can not be there without the mud. Without the mud, there is no lotus possible. There is no happiness without suffering. There is no life without death.
And when the biologists observes the body of a human being, they see that life and death happen at the same time in the body, the body of a human being. They see that life and death happen at the same time in the body. In this very moment, thousands and thousands of cells are dying. When you scratch like this, many dry cells fall down. They have died. And many cells die every moment of our daily life. Because you are so busy, you don't notice that you are dying. If they die, you are dying. You think that you don't die yet, you have to wait for 50 or 70 years later in order to die a death. Not true. Death is not down the road, death is right here and right now. So, death is happening in the here and now at each moment.
And because of the dying of a number of cells, the birth of other cells is possible. So, many cells are being born in the present moment. And we don't have the time to organize a happy birthday for them. So, the fact is that scientifically speaking, you can already see birth and death happening in the present moment. And because of the dying of cells, the birth of cells is possible. Because the birth of cells is possible, the dying of cells is possible. They lean on each other to be.
So, you are experiencing dying and being born in every moment. Don't think you were only born on that moment. That moment written on your birth certificate is just one moment. And that is not the first moment. Before that moment, there were moments you were already there. Before you were conceived in the womb of your mother, you had already been there in your father and in your mother in another form. So, there is no birth, no really beginning and there is no ending.
So, when we know that birth and death are together always, we are no longer afraid of dying. Because at the moment of dying, there is birth also. Birth comes with death. There they can't be separated. This is a very deep meditation. And you should not meditate with your brain alone. You have to observe life during your daily life. And you see birth and death inter-are in everything. Trees, animals, weather, matter, energy.
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