The calls for freedom of press in the mid-seventeenth century, like the earlier calls for freedom of speech, also came mostly from devoutly religious people: Puritans and Nonconformists and their religious-based demands. That religious basis was mostly a desire to disseminate religious preaching and knowledge, and an imperative to do that not only by preaching and other speech but by publishing religious books and pamphlets, in addition to a religious basis in freedom of conscience. John Milton, the trailblazer in seeking "the liberty to know, to utter, and to argue freely according to conscience," tried to extend parrhesia from speech to publications, and built his case in Areopagitica and in other pamphlets on freedom of conscience, on Bible passages, and on similar religious messages. Though Areopagitica is generally described in scholarly literature as unnoticed and overlooked until the end of the seventeenth century, it in fact was relatively widely known, as nearly fifty quotations or allusions show before that century’s end. Besides Milton, other Puritans were the dominant advocates for freedom of press before the end of the seventeenth century, including three who wrote a generation before Milton (an anonymous minister, Leonard Busher, and William Ames), and Levellers and others.

Introduces the central thesis of the book: that freedom of thought, conscience, inquiry, and speech is inviolable for science and politics and sacrosanct to civilization. Who the devil is and what he is due is stated: The devil is anyone who disagrees with you or someone else, and what he is due is the right to speak his mind. The reason we must give the devil his due is explained: for our own safety’s sake. Why? Because my freedom to speak and dissent is inextricably tied to your freedom to speak and dissent. If I censor you, why shouldn’t you censor me? If you silence me, why shouldn’t I silence you? Once customs and laws are in place to silence someone on one topic, what’s to stop people from silencing anyone on any topic that deviates from the accepted canon? The tyranny of censorship must be combatted with the bulwark of freedom.