Shawn Usher beautifully sets the context in Letters of Note: An Eclectic Collection of Correspondence Deserving of a Wider Audience:
Since first being published in 1967— and despite being considered one of the great modern novels—Kurt Vonnegut’s time-hopping, semiauto-biographical, antiwar classic, Slaughterhouse-Five, has been and continues to be banned from classrooms and libraries the world over. This is due to what is often described by those who censor it as its “obscene” content. A different view was held by Bruce Severy, a twenty-six-year-old English teacher at Drake High School, North Dakota, in 1973, who decided to use the novel as a teaching aid in his classroom, much to the delight of his students. The head of the school board, Charles McCarthy, had other ideas, however: He demanded that all thirty-two copies be burned in the school’s furnace. Many of the students protested the decision; some even refused to hand their books back. Their admirable stance was ignored. On November 16, 1973, an angry and disappointed Vonnegut wrote to McCarthy to make his feelings known. His powerful letter failed to generate a reply.
Here's the letter.
November 16, 1973
Dear Mr. McCarthy:
I am writing to you in your capacity as chairman of the Drake School Board. I am among those American writers whose books have been destroyed in the now famous furnace of your school.
Certain members of your community have suggested that my work is evil. This is extraordinarily insulting to me. The news from Drake indicates to me that books and writers are very unreal to you people. I am writing this letter to let you know how real I am.
I want you to know, too, that my publisher and I have done absolutely nothing to exploit the disgusting news from Drake. We are not clapping each other on the back, crowing about all the books we will sell because of the news. We have declined to go on television, have written no fiery letters to editorial pages, have granted no lengthy interviews. We are angered and sickened and saddened. And no copies of this letter have been sent to anybody else. You now hold the only copy in your hands. It is a strictly private letter from me to the people of Drake, who have done so much to damage my reputation in the eyes of their children and then in the eyes of the world. Do you have the courage and ordinary decency to show this letter to the people, or will it, too, be consigned to the fires of your furnace?
I gather from what I read in the papers and hear on television that you imagine me, and some other writers, too, as being sort of ratlike people who enjoy making money from poisoning the minds of young people. I am in fact a large, strong person, fifty-one years old, who did a lot of farm work as a boy, who is good with tools. I have raised six children, three my own and three adopted. They have all turned out well. Two of them are farmers. I am a combat infantry veteran from World War II, and hold a Purple Heart. I have earned whatever I own by hard work. I have never been arrested or sued for anything. I am so much trusted with young people and by young people that I have served on the faculties of the University of Iowa, Harvard, and the City College of New York. Every year I receive at least a dozen invitations to be commencement speaker at colleges and high schools. My books are probably more widely used in schools than those of any other living American fiction writer.
If you were to bother to read my books, to behave as educated persons would, you would learn that they are not sexy, and do not argue in favor of wildness of any kind. They beg that people be kinder and more responsible than they often are. It is true that some of the characters speak coarsely. That is because people speak coarsely in real life. Especially soldiers and hardworking men speak coarsely, and even our most sheltered children know that. And we all know, too, that those words really don’t damage children much. They didn’t damage us when we were young. It was evil deeds and lying that hurt us.
After I have said all this, I am sure you are still ready to respond, in effect, “Yes, yes— but it still remains our right and our responsibility to decide what books our children are going to be made to read in our community.” This is surely so. But it is also true that if you exercise that right and fulfill that responsibility in an ignorant, harsh, un-American manner, then people are entitled to call you bad citizens and fools. Even your own children are entitled to call you that.
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 education 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.