"Those who don't know history are destined to repeat it."
“Those who cannot remember the past are condemned to repeat it.”In his 1905 book The Life of Reason.
It's been attributed to Churchill who apparently never said it - he was significantly more verbose:
"Want of foresight, unwillingness to act when action would be simple and effective, lack of clear thinking, confusion of counsel until the emergency comes, until self-preservation strikes its jarring gong-these are the features which constitute the endless repetition of history."
The meaning is the same regardless. I also happen to think it is hopelessly optimistic, and wrong. We've studied history, we have it written down (at least as much as can be ascertained from the victors who always write the history with themselves as the hero.
I think the problem is not a failure to remember history, but a flaw in human nature that makes us believe that, somehow it will be different this time around. And - it usually is a bit different, it's almost always worse.