In the early Middle Ages, parchment (a type of thin leather from goat or sheep skin) was a common writing surface. It was relatively expensive, but very durable. We're talking about writing books and essays, not letters to Grandma.
If you wanted to write something, but had neither parchment nor money for parchment, you might take a rough stone and rub it over the surface of an already-written parchment to erase what was already written there, and then you could write. Centuries later, scientists discovered that you could, using ultra-violet light in some cases, infra-red in others, still read what had been erased. In still other cases, chemical reactions or sub-atomic particles could bring the erased writing back to life.
In this way, books and essays which have been lost for centuries can be recovered ... a sort of scientific detective work in the service of history and literature.
A "palimpsest" is a piece of parchment which has been erased and re-written. The task is to figure out what was erased.
Major universities have several palimsest readers, people who do this kind of scientific investigation.
Would you like to be a palimpsest reader?
