Descartes' statement of "Cogito ergo sum" marked a marked departure from what was the philosophy of his time. 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. This is where Descartes begins his surprising point: “And so, having thought well and carefully examined all things, we must finally conclude that this statement, Ego sum, existing ego, is necessarily true whenever I propose to apprehend it mentally. .” With this statement he affirms its existence and later concludes that it was a res cogitans – a thinking thing, “that is, a mind, understanding, or reason of which hitherto was unknown to me. They are a real and truly existing thing. Descartes broke with the old philosophy and gave it a new beginning. In particular, since his system of truth originated from his own thinking and analysis, he no longer wishes to rely on the ideas of previous philosophers. He is clearly determined to discover in his own reason the basis of intellectual certainty. In proving Descartes I will use the 'Cogito' to prove the existence of God. Descartes intuits this self-evident proposition and at the same time simultaneously deduces his own existence from it. By an act of simple mental vision, he clearly and distinctly perceived that he existed from a clear and distinct premise about what he thought. For him, the Cogito responds to the criterion of truth previously formed by him. This proposition cannot be undermined because it is a privileged truth and not subject to the "evil genius". This truth is also indubitable. Here it must be specified that he thought not so much in the order of existence but r...... 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 that idea is that of a supremely perfect being. God would not be a perfect being if there were the impossibility of his existence. Consequently, 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 without limitations. This argument does not depend on Descartes first recognizing his existence according to the prior proof of God's existence. God becomes the subject and existence the predicate. God is seen by virtue of His very existence. Such knowledge is clear and distinct and guarantees the truth for Descartes.