From The Art and Popular Culture Encyclopedia
Areopagitica: A speech of Mr John Milton for the liberty of unlicensed printing to the Parliament of England is a prose tract or polemic by John Milton, published November 23, 1644, at the height of the English Civil War. Milton's Areopagitica is titled after a speech written by the Athenian orator Isocrates in the 5th century BC. (The Areopagus is a hill in Athens, the site of real and mythical tribunals. Isocrates hoped to restore the Council of the Areopagus.) Like Isocrates, Milton had no intention of delivering his speech orally. Instead it was distributed via pamphlet, defying the same publication censorship he argued against.
Milton, though a supporter of the Parliament, argued forcefully against the Licensing Order of 1643, noting that such censorship had never been a part of classical Greek and Roman society. The tract is full of biblical and classical references which Milton uses to strengthen his argument. The issue was personal for Milton as he had suffered censorship himself in his efforts to publish several tracts defending divorce (a radical stance at the time and one which met with no favor from the censors).
Interestingly, Milton is not completely libertarian in Areopagitica and argues that the status quo ante worked best. According to the previous English law, all books had to have at least a printer's name (and preferably an author's name) inscribed in them. Under that system, Milton argues, if any blasphemous or libelous material is published, those books can still be destroyed after the fact.
Areopagitica is among history's most influential and impassioned philosophical defences of the principle of a right to free speech.
Some consider Areopagitica worth reading side-by-side with Paradise Lost; a juxtaposition of these texts may yield an intriguing window into Milton's non-conventional theological tendencies.