5 Such powers are there in God; powers which the methods of our reason cannot comprehend, but of which our faith, on the sure evidence of His action, is convinced. We shall find instances of this action in the bodily sphere as well as in the spiritual, its manifestation taking, not the form of an analogy which might illustrate the Birth, but of a deed marvellous yet comprehensible. On the wedding day in Galilee water was made wine. Have we words to tell or senses to ascertain what methods produced the change by which the tastelessness of water disappeared, and was replaced by the full flavour of wine?
It was not a mixing; it was a creation, and a creation which was not a beginning, but a transformation. A weaker liquid was not obtained by admixture of a stronger element; an existing thing perished and a new thing came into being. The bridegroom was anxious, the household in confusion, the harmony of the marriage feast imperilled. Jesus is asked for help. He does not rise or busy Himself; He does the work without an effort. Water is poured into the vessels, wine drawn out in the cups.
The evidence of the senses of the pourer contradicts that of the drawer. They who poured expect water to be drawn; they who draw think that wine must have been poured in. The intervening time cannot account for any gain or loss of character in the liquid. The mode of action baffles sight and sense, but the power of God is manifest in the result achieved.
Source: On the Trinity (New Advent)