Precisely because, given this or that work-to-be-made, there are strictly determined ways of realizing it, ways that depend on the pure exigencies of the work itself and that brook no liberties, the virtue of art, as I just indicated, does not allow the work to be interfered with or immediately ruled by anything other than itself. It insists that it alone shall touch the work in order to bring it into being. In short, art requires that nothing shall attain the work except through art itself. This is the element of truth in the doctrine of gratuitousness. Woe to the artist who is deficient with respect to this exigency of his art, a jealous and fierce exigency, as are all the exigencies of the intelligence and its virtues. Here again we can find in our art a vestige as it were of the Trinity. The Word, says Saint Augustine, is in some way the art of Almighty God. And it is through the Word that the whole of the divine work was made, omnia per ipsum facta sunt. It is through His Word and His art that God attains, rules and brings into being everything He makes. In the same way it is through his art that the human artist must attain, rule and bring into being all his work.
Source: Jacques Maritain, "An Essay on Art"