The 18th century saw two great social revolutions, one in America, the other in France. One of them––the American Revolution––was the outcome of Enlightenment ideas, and was fueled, in particular, by the ideas of John Locke. The other––the French Revolution––was the outcome of anti-Enlightenment ideas, and was fueled , in particular, by the ideas of Jean Jacques Rousseau . These lectures will contrast the ideas of Locke with those of Rousseau, in order to explain the contrast in what these revolutions produced: a free and prosperous America, and a blood-soaked tyrannical France. These lectures, therefore, will offer a case study in the power, for good, of true philosophical ideas, and the destructiveness of false ideas.