The whole letter is at Letters of Note and is well worth the read:
I read in the newspaper that your community is mystified by the outcry from all over the country about what you have done. Well, you have discovered that Drake is a part of American civilization, and your fellow Americans can’t stand it that you have behaved in such an uncivilized way. Perhaps you will learn from this that books are sacred to free men for very good reasons, and that wars have been fought against nations which hate books and burn them. If you are an American, you must allow all ideas to circulate freely in your community, not merely your own.
If you and your board are now determined to show that you in fact have wisdom and maturity when you exercise your powers over the eduction of your young, then you should acknowledge that it was a rotten lesson you taught young people in a free society when you denounced and then burned books–books you hadn’t even read. You should also resolve to expose your children to all sorts of opinions and information, in order that they will be better equipped to make decisions and to survive.
Again: you have insulted me, and I am a good citizen, and I am very real.