Which leads to other important observations about archeology and retaining history. If yesterday's trash has value, how do we keep it from being lost? If an old building is important,  how do we prevent it being destroyed? If we continue to protect history will the artefacts,  like trash, build up to the point where all available space is taken up with artefacts, (just like we are covering the planet with our trash). And if we continue to declare buildings 'historic', what happens as we run out of space for new buildings?