"Mighty little force is needed to control a man whose mind has been hoodwinked..."

I think perhaps of all the things a police state can do to its citizens, distorting history is possibly the most pernicious. For example, I learned for the first time that the United States had not been ruled by a bloodthirsty emissary of Satan before the First Prophet arose in his wrath and cast him out – but had been a community of free men; deciding their own affairs by peaceful consent. I don't mean that the first republic had been a scriptural paradise, but it hadn't been anything like what I had learned in school.

For the first time in my life, I was reading things which had not been approved yet the Prophet's censors, and the impact on my mind was devastating. Sometimes I would glance over my shoulder to see who was watching me, frightened in spite of myself. I began to sense that secrecy is the keystone of all tyranny. Not force, but secrecy... censorship. When any government, or any church for that matter, undertakes to say to its subjects, "This you may not read, this you must not see, this you are forbidden to know," the end result is tyranny and oppression, no matter how holy the motives. Mighty little force is needed to control a man whose mind has been hoodwinked; contrariwise, no amount of force can control a free man, a man whose mind is free. No, not the rack, not fission bombs, not anything - you can't conquer a free man; the most you can do is kill him.

From "Revolt in 2100" by Robert A Heinlein.