John Chrysostom — as excerpted in the Catena Aurea on John 2:5-11

“(Hom. xxii. 2) But why did He not work the miracle before they had filled the waterpots, which would have been much more wonderful; inasmuch as it is one thing to change the quality of some existing substance, another to make it that substance out of nothing? The latter miracle would be the more wonderful, but the former would be the more easy of belief. And this principle often acts as a check, to moderate the greatness of our Lord’s miracles: He wishes to make them more credible, therefore He makes them less marvellous; a refutation this of the perverse doctrine of some, that He was a different Being from the Maker of the world. For we see He performs most of His miracles upon subject-matter already existing, whereas were He contrary to the Creator of the world, He would not use a material thus alien, to demonstrate His own power. He did not draw out the water Himself which He made wine, but ordered the servants to do so. This was for the sake of having witnesses of the miracle; And He saith unto them, Draw out now, and bear unto the governor of the feast.”