— George Santayana, The Life of Reason: Five Volumes in One
Context: Progress, far from consisting in change, depends on retentiveness. When change is absolute there remains no being to improve and no direction is set for possible improvement: and when experience is not retained, as among savages, infancy is perpetual. Those who cannot remember the past are condemned to repeat it.
This famous statement has produced many paraphrases and variants:
Those who cannot learn from history are doomed to repeat it.
Those who do not remember their past are condemned to repeat their mistakes.
Those who do not read history are doomed to repeat it.
Those who fail to learn from the mistakes of their predecessors are destined to repeat them.
Those who do not know history's mistakes are doomed to repeat them.
There is a similar quote by Edmund Burke (in Revolution in France) that often leads to misattribution: "People will not look forward to posterity, who never look backward to their ancestors."