From Descartes' famous line 'I think therefore I am' to Kant's fascinating discussions of morality, the thinkers of the Enlightenment have helped to shape the modern world. Addressing such important subjects as the foundations of knowledge and the role of ethics, the theories of these philosophers continue to have great relevance to our lives. Ranging across Enlightenment thinking from Berkeley to Rousseau, explains important ideas such as Locke's ideas of primary and secondary qualities, Kant's moral rationalism, and Hume's inductive reasoning. Filled with helpful diagrams and simple summaries of complex theories, this essential introduction brings the great ideas of the past to everyone. The critically-acclaimed series provides accessible and engaging introductions to wide-ranging topics, written by experts in their fields.