Life in the world is unpredictable and uncertain.
Life is difficult, short and fraught with suffering.
Being born, one has to die; this is the nature of the world.
With old age there is death; this is the things are.
When fruit is ripe, it may drop early in the morning.
In the same way, one who is born may die at any moment.
Just as all pots made by all the potters End in being broken, So it is with the life of all who are born. Neither young nor old, foolish or wise will escape the trap of death. All move towards death. They are overcome by death. They pass on to another world.
A father cannot save his son or a family its members. Look! With relatives watching, with tears and crying, Men are carried off one by one, like cattle to the slaughter.
So, death and aging are a natural part of the world. Thus, the wise grieve not, seeing the nature of the world.
Source : The Gotama Buddha Sasana Network