This tetrad of the effects of technologies and 
artefacts presents not a sequential process, but 
rather four simultaneous ones. All four aspects 
are inherent in each artefact from the start. The 
four aspects are complementary, and require 
careful observation of the artefact in relation to 
this ground, rather than consideration in the 
abstract.

Marshall McLuhan and Eric McLuhan, Laws of  
Media: The New Science , (Toronto, 1988), p. 99.