Enigma Bench

This sign is on a bench in Sidwell Street, Exeter. The same sign used to be on a wooden bench which was replaced a few years ago, and the sign re-attached. I have no idea where this quote comes from, or why it is on this bench. I don't really want to find out; I like the enigma of it.

Libraries in this palace are ubiquitous.
Their books can be found on corners,
waalls, floors and are signs to palaces
beyond and behind. Yet in the daily
stampedes some books are not read
or even noticed.