From the Commonplace Book: McLuhan on the Arts

"The business of art is...to recover the knowledge of that language which once man held by nature. The problem as to which of the arts should have priority in the work of explaining man and nature had arisen among the pre-Socratic philosophers."
The Classical Trivium, Marshall McLuhan

McLuhan is referencing the historical rivalry that existed among the advocates and practioners of the various arts of the trivium--grammar, dialectic, rhetoric.