Time present and time past
  Are both perhaps present in time future
    And time future contained in time past.
      If all time is eternally present
        All time is unredeemable.
          What might have been is an abstraction
            Remaining a perpetual possibility
              Only in a world of speculation.
                What might have been and what has been
                Point to one end, which is always present.
T. S. Eliot: Burnt Norton (1935)