And we sometimes remember the past differently from what it must have been based on what we know now. For example, I'm quite sure I saw that one of my wife's pill bottles only had three doses left, so I refilled it. But in fact it had nine doses, which surprised me the next day.

Of course I attribute that to faulty memory. But I could say that my memory is of a past that changed due to some decision I made. The older I get, the more my remembered past gets out of whack :)