[129] Perhaps, also, every one of the different ages of life yields in vigour to the one which comes next to it, and so dies before its time, nature by these means teaching us not to fear the death which comes upon all men, inasmuch as we have found it easy to bear the previous deaths, the death that is of the infant, and that of the child, and that of the boy, and that of the youth, and that of the young man, and that of the full grown man, not one of whom exist any longer when old age has arrived.