Er there's a sense also in which memories may not be an individual phenomenon but may be a collective phenomena and if you listen to families reminiscing about things or people who've know each-other for a long time reminiscing about things, different people supply different details, they contradict one-another, they erm fill things in, they say no it can't have been then because um because that was the Christmas when Uncle Sydney had his kidney stones and um y'know stuff like that.