1Is it possible to be certain of anything? If so, how? The father of modern philosophy and the founder of rational method in philosophical thought, René Descartes (1596-1650) sought the answers to these questions and in doing so, addressed the most important of methods of thinking and understanding truth. In Discourse on Method, he applies a scientific approach to philosophy that comprises four principles: to accept only what reason recognizes as clear and distinct; to analyze complex ideas by dividing them into smaller elements; to reconstruct the ideas; and to make accurate and complete enumerations of the data. His Meditations proceed according to this method, exploring the mind/body distinction, the nature of truth and error, the existence of God, and the essence of material things.