Gottfried Leibniz named his metaphysics the system of pre-established harmony, which presupposed the ontological argument. The ontological argument resulted in pantheism. The law of continuity applies what is true of God to every substances, which resulted in monadology. The principle of sufficient reason prompts us to ask why this universe exists, which resulted in optimism. Leibniz thought God is intelligent enough to know the best of all possible universes, benevolent enough to select it and powerful enough to realize it as the existing one, but this being is more than the mere amount of universes whose existence alone the ontological argument can prove. We cannot identify them and apply the system of pre-established harmony to our cognition, benevolence and fulfillment, because we experience mistake, evil and failure.