According to UNESCO estimates, there are approximately one billion people in the world who can neither read nor write. One sixth of the world population has never seen a schoolbook. In contrast, reading and writing in the industrialized nations are such commonplace objects of everyday life that they are completely taken for granted. We are taught to read and write at school, where we gain access to the cultural tool ofwriting, and it is this that forms the basis for all our further leaming activities. The teaching aids used in schools to impart us the skills of literacy are themselves based on the medium of writing. We can all remember what it was like to write things down on paper and in exercise books, to organize our notes in files, and to read up new information in text books. By teaching literacy to the individual, the schools as an institution are laying the foundation stone of literacy skills for entire societies. Many important developmental stages of this process in Europe took place in the Middle Ages, and the schools functioned as a dual participating force in this process. First of all, they were the institution in which competence in literacy was acquired, and they were themselves involved in leaming how best to communicate this task with the aid of the instruments of literacy. These tools, as employed in the schools, have undergone transformation over the centuries. Schoolbooks themselves have also had to adapt, to cope with the demands of literacy.