BOOK 12 -23

Any one individual activity which comes to an end at the appropriate time suffers no harm from its cessation: nor has the agent suffered any harm simply because this particular action has ceased. In the same way,  then, if the total of all his actions which constitutes a man's life comes to an end at the appropriate time,  it suffers no harm from the mere fact of cessation: nor is the agent who brings this series of actions to a timely end exposed to any harm. The time and the term are assigned by nature -sometimes man's own nature, as in old age, but in any case by the nature of the Whole, which through the constant changing of its constituent parts keeps the while world ever young and fresh.