Quotes from Marshall McCluhan:

In the tribal age the ability to hear, touch, taste, and smell were far more developed than the ability to visualize. the right hemisphere of the brain dominated the left. Conformity to the group was the rule and hearing was believing.

The second era, the age of literacy, came about at the invention of the phonetic alphabet. This opened the door to a whole new world. The written word made it possible for information to continuously flow. McLuhan claimed that by learning to read, you become an independent thinker.

The printing press developed by Johannas Gutenberg made visual dependencies widespread. Gutenberg's invention lead to mass production of identical products. McLuhan calls this time period the print age.Samuel Morse takes us to the next time period.

Morse is responsible for the invention of electronic comunication. This type of communication relies on both the ear and hands as major sensory receptors.

The way we live is largely a function of the way we process information. Each invention listed above were turning points in the history of human existence. McLuhan believed that these inventions forced people to change the way they thought about themselves and the world. in other words, McLuhan felt that a medium changes people more than the sum of all the messages.