A quote from The Hidden Power of Electronic Culture:
In a predominantly oral culture, one in which communication is based on face-to-face oral speech, there is no means for storing information or knowledge outside of the mind. As a result, once knowledge is obtained, the culture depends upon the community to both retain and repeat that knowledge. With the introduction of writing, people are affordedthe  luxury to learn and think in isolation without the threat of losing those thoughts. As writing becomes the dominant communication system, people no longer need the …