According to Neil Gaiman, what was the purpose of Fahrenheit 451?

Gaiman opens by stating that people write books about the future for a number of reasons. Such books explore the future because it is more exciting and interesting than the past to imagine, to examine, and to speculate on. Then he says bluntly:

This is a book of warning. It is a reminder that what we have is valuable, and that sometimes we take what we value for granted. 

Gaiman adds that speculative fiction (fiction...

Gaiman opens by stating that people write books about the future for a number of reasons. Such books explore the future because it is more exciting and interesting than the past to imagine, to examine, and to speculate on. Then he says bluntly:

This is a book of warning. It is a reminder that what we have is valuable, and that sometimes we take what we value for granted. 

Gaiman adds that speculative fiction (fiction about the future) is not about predicting the future. Note the present tense of the verb "have" in the quote above. He continues by saying that speculative fiction is actually an assessment of the present. Gaiman calls Fahrenheit 451 a story based on the speculative question, "If this goes on . . ." Bradbury wrote the novel as a warning about the present and how dangerous things in that present might be harder to see in the future. This is illustrated in the novel itself. In Montag's society, most of the people have forgotten what firemen used to do and they have forgotten how valuable books had been. Therefore, it is a novel about how present behaviors could worsen to the point when people will have forgotten the value (in books) they once had. 

For Gaiman, the book was written to warn people about the danger of censorship, and the value of books and independent thinking. It was also a way to transmit thoughts from one generation to the next because, remember, it was written about Bradbury's present (1953). Gaiman concludes by saying that the book is not all about one thing. It is also about what you (the reader) find in the pages. So, it is a warning about the present dangers of censorship. It is a love letter to books. It is a message from one generation to the next. And part of that message is to inspire the next generation of readers to think for themselves and to never forget the value of books.