  Although Descartes sometimes uses formal versions of the ontological argument to achieve his aims, he consistently affirms that God’s existence is ultimately known through clear and distinct perception. The formal versions of the argument are merely heuristic devices, to be jettisoned once one has attained the requisite intuition of a supremely perfect being. Descartes stresses this point explicitly in the Fifth Meditation, immediately after presenting the two versions of the argument considered above: