Immanuel Kant was a German philosopher who is widely considered to be a central figure of modern philosophy. He argued that fundamental concepts structure human experience, and that reason is the source of morality. His thought continues to have a major influence in contemporary thought, especially in the fields of metaphysics, epistemology, ethics, political philosophy, and aesthetics. “The Critique of Pure Reason” is one of the most influential works in the history of philosophy. In this book the author argues that there are synthetic judgments such as the connection of cause and effect - e.g., "... Every effect has a cause." - where no analysis of the subject will produce the predicate.