From this perspective, there have been many errors, regrets, missed opportunities -- mostly because of a lack of information, knowledge, understanding or awareness. I don't think a clean slate is possible -- in its literal or metaphorical sense (and addressing nothing to Bergson's paradoxes directly). It is precisely the slow sedimentation process of the ever receding past pushing down on itself that creates the clean slate of the present. In sum, it is the present to which I look to building my future past. Or, in the words of Kubler-Ross, should you shield the canyons from the windstorms, you would never see the beauty of their carvings.