The Penguin English Dictionary Definition

Palimpsest n a partchment or tablet, resused after earlier writing has been erased.

An object, place, or area that reflects it's history.

"A note on the mystic writing pad"

..."One can think of the wax slab as being like the unconscious, and the fleeting images that appear when the outside world intrudes by way of the stylus could be consciousness. The temptation is then to imagine that when we pull the slide across the screen the image will disappear forever, as if when you leave a gallery the images can be evacuated and then conveniently replaced with perceptions of tea and cakes in the cafeteria.

As Freud pointed out, however, the impressions made by the stylus remain on the wax; pull away the protective screen and the paper behind it, and you will see the indentations, ripples of the history of the wax made from marks upon marks that press into a bumpy mess. And a consequence of this uneven surface is that whenever a line is drawn on the cellophane, the history of past impressions is present in the gaps; in these imperfections of consciousness there is, every time, the unconscious..."

Parker, I. (2006) Making Love to My Ego: Castlefield Gallery Productions