The automobile ended the age of the horse and 
buggy, but these returned with new significance 
and experience as the movie “Western.” The 
tetrad—the four laws considered simultaneously, 
as a cluster‚ is an instrument of revealing and 
predicting the dynamics of situations and 
innovations. Nevertheless the usual “archetypal” 
explanations are inadequate because they regard 
the archetype as a figure minus a ground. . . . Both 
the retrieval and reversal aspects of the tetrad 
involve metamorphosis . . .

Marshall McLuhan and Eric McLuhan, Laws of  
Media: The New Science , (Toronto, 1988), p. 105.