For the users of libraries, the freedom of expression give them the possibility to travel among all the visions, the imaginary journeys, the host of persons populating works of fiction, the horizons of knowledge discussed and analyzed in scholary works. Indeed, libraries themselves are vessels for the discovery of the boundless world of ideas, as it has been expressed in words on a page, tracks on a record, pictures on a real and the magnetic or optical patterns of computer disks.