Phenomena of birth and death
Since we were born, life is coming into “make a living”, but nobody can be totally sure how long he will live, because the living conditions are changing in uncertainty. Just like a bud, it seems it is easy and natural to grow into a flower, but only when all the conditions gather and transform well constantly, can the bud possibly become a flower. We think the “child I”, “fellow I” and “old I” are the “same I”, and ignore that the “child I” is fading into the “fellow I”, and the “old I” is the declining of the “fellow I”, neither of them used to stay there. Just like a bud, when the conditions of a bud just stay there without changing, the bud can never become a flower. But when it becomes a flower, it will not be the bud any more. The death of the former form is the birth of the later one. So that the “make a living” is “full of death”, in other words, because of death we live and grow!
Simultaneous birth and death
Not only phenomena (physical or mental) can not keep in one form for a split second, but also the moment of birth and death is nowhere to stay. The dependent arising conditions are changing all the time, the dependent arisen birth need not stay to wait for the dependent arisen death, because the so called birth is “dying” at the same time. And the dependent arisen death need not to wait for the dependent arisen birth, the so called death is “born” at the same time.
No birth and no death
So the name and concept of “birth and death” is a trick made by our illusive view about phenomena and is not the reality of what is really happening. But this kind of illusive view has grown quite deep into our mind, and it becomes so real that we can’t accept that “no birth and no death” is just the reality of the truth. We can’t bear the solution without an origin.
But why did Buddha say “to recover the original mind or original nature”? This “origin” here is not a “real start” or “eternal source”, but means “the reality of the truth is ever like that and always there”. Just like what the Heart Sutra notes: "All phenomena are marked with emptiness. They are neither produced nor destroyed, neither defiled nor pure, neither increasing nor decreasing...... "