The effect of a new staple or natural resource 
upon an economy is much the same as the effect 
of a new medium. But the sense in which a new 
medium is a staple depends upon recognizing that 
media are the technological externalization of our 
senses. Such was phonetic writing. Such is radio. 
When electronics makes possible access to the 
human senses as natural resource, the whole 
nature of commodity and of services undergoes 
transformation.

Marshall McLuhan to Peter Drucker, April 26, 
1960, Letters of Marshall McLuhan  , (Toronto, 
1987) p. 270.