As Gregory House shows us each week (more frequently if you gots enough cable channels) a diagnosis can come oh-so-close yet still be all wrong. Which reminds me of:
"Those who cannot remember the past are condemned to repeat it." George Santayana
People can remember the past, yet misinterpret it.
People can remember the past, yet put themselves above it. How many movies (*cough*DancesWithWolves*cough*) are built on the assumption that if I or someone like me went back to the past I/the person like me would never do the bad things stupid people did back then. Which is nothing new.
People can remember the past, yet distort it.
The use of history requires all of the diagnostic histrionics of Dr. House and his team. Yes, Santayana is right that accurate memory must be in place. But to avoid repeating the past requires much more.