Freedom of the mind requires not only, or not even especially, the absence of legal constraints but the presence of alternative thoughts. The most successful tyranny is not the one that uses force to assure uniformity but the one that removes the awareness of other possibilities, that makes it seem inconceivable that other ways are viable, that removes the sense that there is an outside.
— Allan Bloom, The Closing of the American Mind
I saw the part in bold quoted online and knew I had to share it here. As usual, my cynical side insisted I confirm that the attribution was correct (so many aren't), so I was able to include a litte more of the text.
One more book for my already impossible need-to-read list.