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. The well-known example of this is the crazy genetics preached in the USSR by Lysenko, which in the absence of discussion (his opponents were exiled to Siberia) compromised the harvests for twenty years. 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.

The Drowned and the Saved (1986)