Oral communication, in life as in school, could refer to written texts. It could gain teaching authority in knowledge and understanding of these texts. Teaching was conceived as a transmission process. Learning was mechanical acceptance, and understanding the scholar was a later reward and confirmation of adulthood. This changes fundamentally with the printing of books. Books recommend themselves for "self-learning." For schools, this means that teaching can develop self-learning skills and then reckon with them. Teaching and learning are now completely different modes of operation, and their integration, which is nevertheless to be striven for, becomes a problem. The resulting reformulated pedagogy is no longer measured only in terms of getting the material into the children's heads, but in terms of developing the ability to learn. The "cram school" falls into disrepute. The school is now in demand as an educational institution. Accordingly, natural education, which accompanies the aging process, is now recommended only for an initial phase in which children are still children. And this is followed by the phase of school attendance and study, in which education is promoted in the sense of the earliest possible independence in dealing with reading.
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Luhmann, Niklas (1991). Das Kind als Medium der Erziehung. doi 
, p. 33.