For 10 points, name
 this book that draws on A Treatise of Human Nature, also by David Hume.
In this work, one character pretends to be Epicurus defending his religious beliefs. In an earlier section,
 the author of this work declares that mathematical sciences are Relations of Idea, which are distinct from
 Matters of Fact. Largely a reaction to the inductive reasoning of Locke, this work considers cause and
 effect in arguing that we understand complex ideas because of simple ideas, a concept called the Copy
 Principle. It later argues that miracles can't exist because they contradict the laws of nature, and it earlier
 presents an exception to the Copy Principle by imagining a "missing shade of blue." For 10 points, name
 this book that draws on A Treatise of Human Nature, also by David Hume.
In this work, one character pretends to be Epicurus defending his religious beliefs.
An {Enquiry} Concerning {Human Understanding}