Edmond Locards Exchange Principle states:

“Wherever he steps, whatever he touches, whatever he leaves, even unconsciously, will serve as a silent witness against him. Not only his fingerprints or his footprints, but his hair, the fibers from his clothes, the glass he breaks, the tool mark he leaves, the paint he scratches, the blood or semen he deposits or collects. All of these and more, bear mute witness against him. This is evidence that does not forget. It is not confused by the excitement of the moment. It is not absent because human witnesses are. It is factual evidence. Physical evidence cannot be wrong, it cannot perjure itself, it cannot be wholly absent. Only human failure to find it, study and understand it, can diminish its value.”This statement is so full of implications. It is so rich and it really resonates with me, instigating a whole host of thoughts and questions some of which (in no particular order and with no attempt to make sense) follow:We are constantly leaving traces; more or less perceptibly and more or less permanently. Sometimes the most perceptible will be the least permanent and vice versa: the instantly evident footprint in the sand, the imprint of our body in a soft comfortable chair compared with the gradually accumulating imprint of footprints on stone steps – only over years are the effects seen and yet their presence is evidence of the fact that each footprint is making it’s mark – each one eradicating the last, so that the lack of it becomes evidence of it – the absence of step is testament to the one time presence of foot, so to speak.Might we be able to reconstruct our own histories via the traces we’ve left? (archaeologists do). Many, maybe most, will have vanished under those that others have left, but intermittent traces might be found – the things we’ve written, built, broken, buried.The traces left on us by our contact with the world – could we trace our history via those? The archaeology of the body. The wounds, scars – the more obvious instant marks of the world upon us and the accumulated traces, the gradual changing of the muscles and tendons and the toll our individual postures (being also the effect of our response to our lives) take on our skeletons; the marks of our physical and emotional lives that the wear and tear on our skin, livers and hearts are testament to.The traces of others upon us and our traces upon them – the more ongoing and clearly significant traces of those who have somehow shaped our lives through our responses to them and the less obvious more transient meetings and encounters whose traces are less easily seen or felt. Maybe we could build a picture of our lives from the stories of all those who we no longer know, from the chance encounters, the looks and bumps into strangers that remember us – that those people with whom we’ve left a trace might write our alternative history – a history of things we’ve forgotten and perspectives we can’t have – of our casual effect on others and the world – the plastic bag tossed anway and later found in the stomach of the cow that choked on it (or the accident avoided because of the delay we accidentally caused – the marks unmade).The encounters we have, the moments of brief and passing exchange we have with people as we make our way through life – what traces are they leaving with us and us with them? – Like the stone steps’ gradual erosion, are these peripheral encounters accumulating within our subconscious imaginations to make us who we are becoming  – like the sub plot, the underlying subliminal narrative to the main theme of our lives – providing the invisible footnotes that underscore our lives.Our exchanges with people are so full, what takes place in all those glances, those momentary meetings of eyes, those brief encounters? I think of looking at photographs – of flicking through images and the amount of information I’m taking in before moving on to the next – all in seconds, things which may later be recalled when I almost feel I’ve forgotten them. And something like this is taking place out on the street, in the supermarket, on the train – the subconscious film we make of our lives – so much information as I see you and you see me. We could consider all the things that we take in, the minor and the major events and exchanges that happen. All these characters and occurrences in our lives are making their impression upon us and we on them. They are in us along with everything else and a part of the store of background information that we’re constantly referring to as we proceed.Impression – the impression we leave upon something – our fingerprints, the fingered pages, the coffee stained cover of the book we’re reading, the impression we make on another person… The first impression, the impressions over time, each next impression somehow eradicating something of the last, so that we are rebuilding our impressions as we go along – something like the stone steps.The impression someone, or something makes on us, or that we take from our meeting with someone. The part that we’re aware of or focus on and the part that is absorbed/assimilated unnoticed.I think of the idea of mindfullness – the idea of being aware of how we feel what we perceive, what we give our attention to noticing as we move through life – all the things that miss our attention and yet make an impression – as if while one part of our perception machine is looking one way, another part is sneaking something in the back door – we don’t notice that smell at the time but later when we smell it again, we’re reminded of the earlier unnoticed event – “oh yes, I didn’t notice it at the time, but now you come to mention it”…If I notice more about my passage through the world, what will it mean? – how will I be changed if I notice that change is happening?