G.K. Chesterton is best known for his apologetic works Orthodoxy and The Everlasting Man.
But the work that earned him some of the highest praise was Saint Thomas Aquinas: The Dumb Ox.
The story of how Chesterton wrote the book is well known in Chestertonian circles. It is said that he dictated the book over the course of a week while casually flipping through a few biographies of Aquinas that a friend in London had sent him. The end result prompted Etienne Gilson, one of the 20th centuries foremost Aquinas scholars, to remark: "I consider it as being without possible comparison the best book ever written on St. Thomas. Nothing short of genius can account for such an achievement.”
Chesterton was no professional philosopher.But that didn’t prevent him from grasping the essence of Thomas’s philosophy:
Without pretending to span within such limits the essential Thomist idea, I may be allowed to throw out a sort of rough version of the fundamental question, which I think I have known myself, consciously or unconsciously, since my childhood. When a child looks out of the nursery window and sees anything, say the green lawn of the garden, what does he actually know; or does he know anything? There are all sorts of nursery games of negative philosophy played round this question. A brilliant Victorian scientist delighted in declaring that the child does not see any grass at all; but only a sort of green mist reflected in a tiny mirror of the human eye. This piece of rationalism has always struck me as almost insanely irrational. If he is not sure of the existence of the grass, which he sees through the glass of a window, how on earth can he be sure of the existence of the retina, which he sees through the glass of a microscope? If sight deceives, why can it not go on deceiving? Men of another school answer that grass is a mere green impression on the mind; and that he can be sure of nothing except the mind. They declare tat he can only be conscious of his own consciousness; which happens to be the one thing that we know the child is not conscious of at all. In that sense it would be far truer to say that there si grass and no child, than to say that there is a conscious child but no grass. St. Thomas Aquinas, suddenly intervening in this nursery quarrel, says emphatically that the child is aware of Ens. Long before he knows that the grass is grass, or self is self, he knows that something is something. Perhaps it would be best to say very emphatically (with a blow on the table), “There is an Is.” That is as much monkish credulity as St. Thomas asks of us at the start. Very few unbelievers start by asking us to believe so little. And yet, upon this sharp pin point of reality, he rears by long logical processes that have never really been successfully overthrown, the whole cosmic system of Christendom.”
Chesterton proceeds to point out that any given thing at any given moment is something, but it is not everything it could be. There is a fullness of being—a perfection of being—upon which the existence of all other objects depends. That Being is God.
Whether Chesterton’s articulation of Thomism and its emphasis on Ens—that is, Being—is correct is a question for the philosophers. That it shaped Chesterton’s worldview is undeniable.
In Orthodoxy, he writes:
“Such, it seemed, was the joy of man, either in elfland or on earth; the happiness depended upon not doing something which you could at any moment do and which, every often, it was not obvious why you should not do. Now, the point here is that to me this did not seem unjust. If the miller’s third son said to the fairy, “Explain why I must not stand on my head in the fairy palace,” the other might fairly reply, “Well, if it comes to that, explain the fairy palace.” If Cinderella says, “How is it that I must leave the ball at twelve?” her godmother might answer, “How is it that you are going there till twelve?” If I leave a man in my will ten talking elephants and a hundred winged horses, he cannot complain if the conditions partake of the slight eccentricity of the gift. He must not look a winged horse in the mouth. And it seemed to me that existence was itself so very eccentric a legacy that I could not complain of not understanding the limitations of the vision when I did not understand the vision they limited. The frame was no stranger than the picture. The veto might well be as wild as the vision; it might be as startling as the sun, as elusive as the waters, as fantastic and terrible of the towering trees.”
Chesterton's point is a moral one, but it rests on the metaphysic; the experience of joy does not stem from discovering what a thing is, but simply that it is. The doctrine of conditional joy is predicated upon the doctrine of conditional being, and it is precisely that doctrine that Thomism emphasized. The universe could have been other than it is--the real mystery is that it is.
It is Thomism and its emphasis on the contingent nature of human reality that undergirds Chestertonian wonder. The fundamental fact of the universe is that there is something rather than nothing, and that something is intrinsically good. Chesterton, though dressed in Victorian garb, is actually a medieval.