Nationalism didn’t exist in Europe until the Renaissance, when typography enabled every literate man to see his mother tongue analytically as a uniform entity. The printing press, by spreading mass-produced books and printed matter across Europe, turned the vernacular regional languages of the day into uniform closed systems of national languages — just another variant of what we call mass media — and gave birth to the entire concept of nationalism.
The Playboy Interview: Marshall McLuhan « NextNature.net 11:13am on January 21, 2015