I think we fixate on memory as it is in effect, the sum total of things which cannot be changed. It’s such a powerful experience, because as we have all expressed in various ways, there are certain things which retain their clarity over the course of years: even when recalled decades later, they remain perfect (or their imperfections are not evident which is much the same thing). Memory is like the present, but with one insistent and pernicious flaw – we can do nothing about it whatsoever.
It is the dichotomy between remembrance and experience I suppose that makes the whole question so prevailing and pertinent – knowing exactly what a certain moment now passed felt like - to a precise degree - but being unable to encounter the moment in anything other than an observational sense. Although memory is contained within the same set of sensory restraints as our contemporary experience, it is more like a movie that plays across our eyes, our ears, even our noses. You can’t punch a memory. It is not even a question of this challenge only presenting within the bounds of desirable recollection; the fact that you remember a painful time, or a frustrating time does not limit the subconscious desire to interact with it again, it merely alters the motivation. Rather than reliving pleasant times again in order to revisit experienced pleasure, it simply becomes a matter of wishing to alter unpleasant episodes.
I think Nabokov had it wrong when he titled his autobiography ‘Speak, Memory’, in that he suggests the memory needs to be commanded to release its contents. It needs no such thing, whether we like it or not, the little home movie of concrete experience plays non-stop somewhere, only occasionally drowned out by the present or by contemplation of the future. It is that weight of certainty, when all else is contingent, that gives it such definition.