For a long time preservation was considered the main function of libraries. Today's library still must act as cultural memory for our society. But what shall we do with this memory? Leaving aside the question of the physical medium (paper or otherwise) we must ask ourselves whether the new information and communication techniques do not alter our mental patterns, at least in two ways. First, in providing a considerable increase in storage capacity which requires constantly to look for new filters so as to recreate a form of rareness. Secondly, in giving greater impoortance to short-lived «current events» over a lasting memory. What are the chances of retaining a living culture between erudition and dispersion ?