God exists, nor do we prove it a priori. But we do prove it a posteriori, i.e., from the things that have been created, following an argument from the effects to the cause: namely, from things which are moved and cannot be the adequate source of their motion, to a first unmoved mover; from the production of the things in this world by causes subordinated to one another, to a first uncaused cause; from corruptible things which equally might be or not be, to an absolutely necessary being; from things which more or less are, live, and understand, according to degrees of being, living and understanding, to that which is maximally understanding, maximally living and maximally a being; finally, from the order of all things, to a separated intellect which has ordered and organized things, and directs them to their end. The metaphysical motion of the Divine Essence is correctly expressed by saying that it is identified with the exercised actuality of its own being, or that it is subsistent being itself. And this is the reason for its infinite and unlimited perfection. By reason of the very purity of His being, God is distinguished from all finite beings. Hence it follows, in the first place, that the world could only have come from God by creation; secondly, that not even by way of a miracle can any finite nature be given creative power, which of itself directly attains the very being of any being; and finally, that no created agent can in any way influence the being of any effect unless it has itself been moved by the first Cause. Criticism In his Against Henry, King of the English, Luther criticized the use of the proof by assertion and a reliance on style over substance in the Thomist form of disputation, which he alleged as being, "It seems so to me. I think so. I believe so." Luther also argued that the Thomist method led to shallowness among theological debates in England at the time. Thomism was criticized by Bertrand Russell in A History of Western Philosophy (1946). Besides this, neo-scholasticism in general, including Thomism, is criticized by some Catholics. See also Criticism of the Catholic Church#Nature of theology Brian Davies Peter Kreeft Brian Leftow List of Thomist writers (13th–18th centuries) Alasdair MacIntyre Rule according to higher law Rule of law School of Salamanca Thomistic sacramental theology Thomistic Institute