Memory is vital to experience. Without memory, we are not us. If we could not remember past events, we could not learn or develop language, relationships, nor personal identity (Eysenck, 2012).
There is a concept in brain science that humans have a limited memory. That makes sense, the amount of information taken in, on a daily basis, is more than many people in the deep past took in a year. Some people argue that they have a photographic memory, but, every person's memory lies to them. And many do not see how it could do such a thing.
“Our memory is a more perfect world than the universe: it gives back life to those who no longer exist.” Guy de Maupassant
How is this possible? For one thing, we remember what is important, but our memories are biased by our life views and beliefs. It is certainly true that one remembers what they do for different reasons. Remembering a horrific event is generally more clear than a happy one, because of the manner in which it is recalled. We are less likely to remember specifics if they do not matter.
Eyewitnesses of crime have in the past been given a greater sway of importance than a theory of motive, chance to act, likelihood of committing of a crime by the offender. The reason was that the victim or the eyewitness have a desire to see the right person penalized, and only a fool or asshole would wish the Justice system try an innocent person for the same. This is based upon a truism, but that doesn't mean it is correct. There is evidence that eyewitnesses have a memory of the event also colored by what they know before the event, and by the event, and later by their reasons for reporting it.
A prime example of eyewitness failures is found in rape events where DNA proves another man did the deed. (I say man, not in any assault of males, but in the de facto truth that they are the majority, by far, of such crimes.) DNA has changed the results of numerous criminal results where the previous convictions were arrived at by eyewitness reports.
"I can only note that the past is beautiful because one never realises an emotion at the time. It expands later, and thus we don't have complete emotions about the present, only about the past." Virginia Woolf
We remember because it is part of creating our overall self, this is important. But our memories are rarely true, so much as they are truish. Someone I knew remembered for a fact that a certain baseball manager was the one who took a team to the World Series. The person was rather unwilling to learn the difference but upon being lectured toward, I went and photocopied a page from the Baseball Encyclopedia. I found the exact dates, the events, and made a presentation to the person. That person called me an asshole, and 10 years later I heard them repeat the same falsehood. The manager was a good one, and he did take two teams to the playoffs, but he never managed them into the World Series. It honestly didn't matter to me until I was lectured upon his version of the truth, so it isn't important what manager, what team, and who held the falsehood. The truth was that he liked this manager, and didn't prefer to know the truth.
“Remembrance of things past is not necessarily the remembrance of things as they were.” Marcel Proust
When you are certain someone is wrong, because they remember it being true, you might be right. But, your memory itself might be at fault. Before debating learn a fact, and return to the debate armed for battle. Facts are just pieces of information, neither positive nor negative. But your memory is biased.
“Memory is more indelible than ink.”Anita Loos
Do not assume you have an unbiased memory, because everyone's memory is biased.