Communication

In countries and epochs in which communication is impeded, soon all other liberties wither; discussion dies by inanition, ignorance of the opinion of others becomes rampant, imposed opinions triumph. ...  Intolerance is inclined to censor, and censorship promotes ignorance of the arguments of others and thus intolerance itself: a rigid, vicious circle that is hard to break.

-- Primo Levi (1919-1987), Italian chemist and author, holocaust survivor, The Drowned And The Saved (1986)