“If some books are deemed most baneful and their sale forbid, how, then, with deadlier facts, not dreams of doting men? Those whom books will hurt will not be proof against events. Events, not books, should be forbid.”

Source: The Valley of Bones

As quoted in Michel Foucault (1991) by Didier Eribon, as translated by Betsy Wind, Harvard University Press, p. 282
Context: There are more ideas on earth than intellectuals imagine. And these ideas are more active, stronger, more resistant, more passionate than "politicians" think. We have to be there at the birth of ideas, the bursting outward of their force: not in books expressing them, but in events manifesting this force, in struggles carried on around ideas, for or against them. Ideas do not rule the world. But it is because the world has ideas (and because it constantly produces them) that it is not passively ruled by those who are its leaders or those who would like to teach it, once and for all, what it must think.

Blood Meridian (1985)

42 min 33 sec
Variant: A book is proof that humans are capable of working magic.
Source: Cosmos: A Personal Voyage (1990 Update), The Persistence of Memory [Episode 11]
Context: What an astonishing thing a book is. It's a flat object made from a tree with flexible parts on which are imprinted lots of funny dark squiggles. But one glance at it and you're inside the mind of another person, maybe somebody dead for thousands of years. Across the millennia, an author is speaking clearly and silently inside your head, directly to you. Writing is perhaps the greatest of human inventions, binding together people who never knew each other, citizens of distant epochs. Books break the shackles of time. A book is proof that humans are capable of working magic.

Source: Memoirs Of A Bird In A Gilded Cage (1969), CHAPTER 8, Centennial summer, p. 174

Source: Good Omens: The Nice and Accurate Prophecies of Agnes Nutter, Witch

As quoted in "Vonnegut's Blues For America" Sunday Herald (7 January 2006)
Various interviews

Vol. I, ch. 11
Lady Holland's Memoir (1855)