Without Freedom of Thought, there can be no such Thing as Wisdom; and no such Thing as public Liberty, without Freedom of Speech; which is the Right of every Man, as far as by it, he does not hurt or control the Right of another. And this is the only Check it ought to suffer, and the only bounds it ought to know. This sacred Privilege is to essential to free Governments, that the Security of Property, and the Freedom of Speech always go together; and in those wretched Countries where a Man cannot call his Tongue his own, he can scarce call any Thing else his own. Whoever would overthrow the Liberty of a Nation, must begin by subduing the Freeness of Speech; a Thing terrible to Public Traitors.
Cato's Letters, John Trenchard and Thomas Gordon (Letter Number 15, Freedom of Speech, That the Same is inseparable from Public Liberty, February 4, 1720)