Five hundred years before Christ was born, the Greek philosopher Heraclitus told his students that "everything changes except the law of change". He said: "You cannot step in the same river twice." The river changes every second; and so does the man who stepped in it. Life is a ceaseless change. The only certainty is today. Why mar the beauty of living today by trying to solve the problems of a future that is shrouded in ceaseless change and uncertainty-a future that no one can possibly foretell?
Dale Carnegie