At thirty, man suspects himself a fool,
  Knows it at forty, and reforms his plan;
    At fifty, chides his infamous delay,
      Pushes his prudent purpose to resolve,
        In all the magnanimity of thought;
          Resolves, and re-resolves, then dies the same.
            And why?  because he thinks himself immortal,
              All men think all men mortal but themselves.
 — Edward Young
  Mortality