Those who cannot remember the past are doomed to repeat it.

Related:

• Those who cannot remember the past are condemned to repeat it.
  George Santayana, The Life of...
• Progress, far from consisting in change, depends on retentiveness.
  Those who cannot remember the past are condemned to...
• Those who cannot remember the past are condemned to repeat it.
  George...
• Those who learn nothing from history are doomed to
  repeat it. --...
• Those who fail to repeat history are doomed to
  study it...
• Life is not a spectacle or a feast; it is a predicament.
  George...
• McKernan's Maxim:
  Those who are unable to learn from past meetings are...