Is it possible to be certain of anything? If so, how? The father of modern philosophy and the founder of rational method in philosophical thought, Rene 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 recognises as "clear and distinct"; to analyse 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.