The truth is that even big colections of ordinary books distort space,as can readily be proved by anyone who has been around a really old fashioned secondhandbookshop,one of those that looks as though they were designed by M. Escher on a bad day and has more staircases than storys and those rows of shelves which end in little doors that are surely too small for a full sized human to enter. the relevant equation is=Knowledge=power=energy=matter=mass; a good bookshop is just a genteel black Hole that knows how to read

"Guards! Guards!'
By Terry Pratchett