Censorship always defeats its own purpose, for it creates, in the end, the kind of society that is incapable of exercising real discretion, incapable, that is, of doing an honest or intelligent job, and thus guarantees a steady intellectual decline.

Henry Steele Commager (1902-1998) American historian, writer, activist

Essay (1953-02-21), “Is Freedom Really Necessary?” Saturday Review
    (Source)

Based on a discussion by the American Round Table, New York City (1951). Collected as "Free Enterprise in Ideas," Freedom, Loyalty and Dissent (1954).