Descartes discovers that he has an idea of perfection. He then argues that such an idea implies a cause. However, the thing that caused it must have as much ‘reality’, and that includes perfection, as the idea itself. This implies that only a perfect cause, that is, God, will do. Hence God exists, and has left the idea of perfection as an innate sign of his workmanship in our minds, like a craftsman leaving a trademark stamped in his work.
