It was the invention of printing (of the mass media, if you like) that began modern social and political history.
Contemporary psycho-social researchers see the invention of printing and later expansions of the media as in some way an extension of human consciousness. It's obvious that a dictionary, or a thesaurus, or even a grammar, can be used by humans to underpin their linguistic resources, and that libraries and other stores of content are in some sense supplementary to the internal cognitive resources of the human brain.
Merlin Donald calls the totality of such external content the 'External Symbolic Storage System' or ESSS, and distinguishes it from the preceding 'External Memory Field' or EXMF, which is made up of early, external stores of symbolic content and the possibility of manipulating them, often graphically. Donald lists external uses of symbolism in addition to language as such, including musical notation, geographic maps, military plans, geometric concepts, astronomical lists, calendars and clocks, architectural drawings, and a number of more recent types of symbolic storage (eg choreography).
Although the existence of the ESSS as a major component of human cognition may perhaps be dated to the time of the Ancient Greeks, the invention of printing in the late Middle Ages can be seen as the moment that the ESSS started to become culturally dominant in human society. Donald: 'The number of items stored in collective human experience has grown exponentially with the development of the ESSS, both because the encoded knowledge of the past can be better preserved and because the the process of producing ESSS entries has resulted in a huge industry for generating, inventing and mass-producing exograms.'
Donald's eventual point is that human cognitive faculties have had to adapt away from controlling and sourcing the stored contents of the brain to become a management facility for the enormous ESSS. This is of course reflected in changes in the education process: children nowadays are decreasingly taught knowledge as such; instead, they are taught how to source and use knowledge. Or at least, they should be – in practice education has lagged behind the growth of the ESSS.
Physical means of extending linguistic consciousness have been supplemented by other types of recording technique, including video, DVD, movies, and computer storage. All these add to the reach of consciousness. It's not unreasonable to see the expanded reach of consciousness as an evolutionary adaptation that adds to the fitness of individuals, the groups they belong to, and eventually society as a whole.
Alongside the development of storage media has come an expansion in the means of communication that are available to humans. The telephone, television, radio, the humble fax and mobile phones can all be seen as extensions of the basic senses with which biological evolution had equipped humans. With these expanded senses we can explore the growing external content universe at will.
The coping-stone of this pyramid of extra awareness is of course the Internet. A normally well-educated human can use the Internet to access large portions of the accumulated knowledge of humanity, and to apply it to life situations. And unlike other inventions that have increased human consciousness, the Internet plays to the strength of groupishness.
Long before the Internet, however, the invention of mass media led to the age of the Nation State.