The guarantee of free speech enshrined in the U.S. Bill of Rights draws upon two millennia of Western thought about the value and necessity of free inquiry. Acclaimed legal scholar George Anastaplo traces the philosophical development of the idea of free inquiry from Plato's Apology to Socrates to John Milton's Areopagitica. He describes how these seminal texts and others by such diverse thinkers as St. Paul, Thomas More, and John Stuart Mill influenced...