" For the meaning of life differs from man to man, from
day to day and from hour to hour. What matters, therefore,
is not the meaning of life in general but rather the
specific meaning of a person's life at a given moment[....]
Everyone has his own specific vocation or mission in life
to carry out a concrete assignment which demands fulfillment.
Therein he cannot be replaced, nor can his life be
repeated. Thus, everyone's task is as unique as is his
specific opportunity to implement it."
What proof or theory can be put forward to support this statement?