Almost every American - from the learned historian to the school child - can name the men who were the leaders of the American Revolution and helped create the documents that are the basis of our government. These forefathers, as we call them, include such greats as Patrick Henry, Thomas Jefferson, Benjamin Franklin, John Hancock, George Washington, and John Adams. But what many people don't know is that our forefathers had a forefather - a man whose political theories and writings inspired and guided the American revolutionaries, from concept to constitution. His name was John Locke.

Locke was known, and is still admired today, for his two greatest works: An Essay Concerning Human Understanding; and Two Treatises on Government. The first of these works, Essay Concerning Human Understanding, he started at the age of 39 and completed and published almost twenty years later when he was 58. In this essay...