"She had learned that over the ages various metaphors had been used for explaining memory, all of them attempts to understand how the mind worked. There were seals leaving traces on soft wax; vast storehouses with many chambers and ranks of pigeonholes, some secret; elaborate palaces with thousands of rooms each named. There were metaphors from photography in which memory acted like a chemical, leaving ghostly images behind; and from archaeology with its shards and relics, all needing sifting and reassembly. Meanwhile, from the digital world came hard and soft discs and neural nets. There were also homunculi and mystic writing pads in which scratchy trces or scars were left on a hard plate that was continually being overwritten."
Lisa Appignanesi, The Memory Man, 2004, p,44