"There is nothing to be learned from a Professor, which is not to be met with in Books."
~David Hume (April 26, 1711 – August 25, 1776), Scottish philosopher, economist, and historian
I don't know how truthful it is, though. Certain things must be taught in person. And knowledge has historically been transmitted orally. I still think it is mostly valid, especially considering the era from which it comes - The Age of Reason.