The paper "Period of Enlightenment " is a great example of an assignment on history. The ‘Age of Enlightenment’ also referred to as the ‘Age of Reason’ issued to describe the existing “trends in thought and letters in Europe and the American colonies during the 18th century prior to the French Revolution” (1789-1799). The writers of that period made use of this phrase quite often because they believed that they were evolving from many centuries of darkness and ignorance into a period that was ‘enlightened by reason, science, and respect for all humanity.’ René Descartes (1596-1650), was one of the people who made great contributions to the Enlightenment period. He was not only a French philosopher but also a great mathematician and scientist whose contributions to the world in Philosophy, Math and Science are highly commendable. Descartes’ first major work titled ‘Essais philosophiques’ (Philosophical Essays) were in the field of philosophy which he wrote in four parts on Geometry, optics, meteors and a discourse on Methods. He made an attempt to apply mathematics to the subject of philosophy, but soon rejected it stating that, “In our search for the direct road to truth, we should busy ourselves with no object about which we cannot attain certitude equal to that of the demonstration of arithmetic and geometry.” (René Descartes) His very famous lines of Cogito, ergo sum, “I think, therefore I am” go to show that he was determined not to say something was true, till he established firm grounds for it. His other valuable contributions were in the fields of science and physiology (blood was a subtle fluid) In Science he discarded the ‘Copernican theory that the universe was a system where planets spin around the sun and formulated his own theory of vortices which portrayed space as a place filled with matter in varying states that spin around the sun. Descartes’ contribution to the field of optics was also a major success where he discovered the fundamental law of reflection which is – “that the angle of incidence is equal to the angle of reflection.” His other most notable contributions are “systematization of analytic geometry, the theory of equations and the method of indices (as in X to the power of 2) to express the power of a number. Therefore, René Descartes is one of those people who brought about tremendous changes through his contributions.