Descartes' assertion that “Cogito ergo sum” marked a radical departure from what the philosophy of his time was. He started from the basic principle of rationalism and concluded that “I think, therefore I exist”. In his Meditation II, Descartes reaches an epistemological zero point. It is here that Descartes begins his surprising statement: "And so, after having carefully considered and carefully considered all things, we must finally conclude that this statement, Ego sum, ego existento, is necessarily true whenever I propose mentally apprehend. .” In this statement he asserts his existence and later concludes that he was a res cogitans – a thinking thing, "that is, a mind of which an understanding or a reason whose terms of meaning were until me unknown here. I am a real and actually existing thing. Descartes broke with the old philosophy and gave it a new start. In particular, because his system of truth comes from his own thinking and analysis, he no longer wishes to rely on the ideas of previous philosophers. He is clearly determined to discover the basis of intellectual certainty in his own reason. By proving Descartes' "Cogito", I will use it to prove the existence of God. Descartes intuits this obvious proposition and at the same time simultaneously deduces his own existence. By an act of simple mental vision, he clearly and distinctly perceived that he exists from a clear and distinct premise from what he was thinking. The Cogito responds for him to the criterion of truth that he has previously formed. This proposition cannot be questioned because it is a privileged truth and is not subject to the “evil genius”. Such a truth is also undoubted. It should be clarified here that he was not thinking so much about the order of existence as about middle of paper......e. He argues that the essence of God implies the existence of God. Although the idea of ​​God is present in the human mind, it is different from other ideas because such an idea is that of a supremely perfect being. God would not be a perfect being if his existence were impossible. Therefore, God's existence cannot be separated from his essence. Its essence is to exist and its existence is necessary. Using the criteria of truth, Descartes notes that he clearly and distinctly apprehends the essence of God as supreme perfection. Such perfection is limitless. This argument does not depend on Descartes first recognizing its existence, as the previous proof of God's existence proves. God becomes the subject and existence the predicate. God is seen by virtue of his own existence. Such knowledge is clear and distinct and guarantees the truth for Descartes.