With no unified slogan, office, or central organizing committee authority, the tea party seems to defy definition. But as tea partiers decide whom to support for the Republican nomination, the principles and goals of the movement will guide the future of the election.

The Tea Party: Three Principles goes beyond the rhetoric to help us understand the substance of the movement. Constitutional law expert Elizabeth Price Foley transcends party divides to provide a serious yet accessible analysis of the principles on which the Tea Party is founded. Rather than tackling its political or pragmatic aspects-the "who," "why," or "how to"-this book explains the misunderstood but critically important "what."

This month, join the Cambridge Book Club as we take a look at the substance of this uniquely American movement. Read the preface, chat with the author, and start a discussion with the reader's guide. Then share your thoughts onFacebook, or chime in on Twitter using the hashtag #cambridgeideas.