Except for light, all other media come in pairs, with one acting as the "content" of the other, obscuring the operation of both.
Marshall McLuhanAll media work us over completely. They are so pervasive in their personal, political, economic, aesthetic, psychological, moral, ethical, and social consequences that they leave no part of us untouched, unaffected, unaltered. The medium is the message. Any understanding of social and cultural change is impossible without a knowledge of the way media work as environments. All media are extensions of some human faculty - psychic or physical.
Marshall McLuhan