EIGHTH ARTICLE [III, Q. 77, Art. 8]
Whether Any Liquid Can Be Mingled with the Consecrated Wine?
Objection 1: It seems that no liquid can be mingled with the consecrated wine, because everything mingled with another partakes of its quality. But no liquid can share in the quality of the sacramental species, because those accidents are without a subject, as stated above (A. 1). Therefore it seems that no liquid can be mingled with the sacramental species of the wine.
Obj. 2: Further, if any kind of liquid be mixed with those species, then some one thing must be the result. But no one thing can result from the liquid, which is a substance, and the sacramental species, which are accidents; nor from the liquid and Christ's blood, which owing to its incorruptibility suffers neither increase nor decrease. Therefore no liquid can be mixed with the consecrated wine.
Obj. 3: Further, if any liquid be mixed with the consecrated wine, then that also would appear to be consecrated; just as water added to holy-water becomes holy. But the consecrated wine is truly Christ's blood. Therefore the liquid added would likewise be Christ's blood otherwise than by consecration, which is unbecoming. Therefore no liquid can be mingled with the consecrated wine.
Obj. 4: Further, if one of two things be entirely corrupted, there is no mixture (De Gener. i). But if we mix any liquid, it seems that the entire species of the sacramental wine is corrupted, so that the blood of Christ ceases to be beneath it; both because great and little are difference of quantity, and alter it, as white and black cause a difference of color; and because the liquid mixed, as having no obstacle, seems to permeate the whole, and so Christ's blood ceases to be there, since it is not there with any other substance. Consequently, no liquid can be mixed with the consecrated wine.
On the contrary, It is evident to our senses that another liquid can be mixed with the wine after it is consecrated, just as before.
I answer that, The truth of this question is evident from what has been said already. For it was said above (A. 3; A. 5, ad 2) that the species remaining in this sacrament, as they acquire the manner of being of substance in virtue of the consecration, so likewise do they obtain the mode of acting and of being acted upon, so that they can do or receive whatever their substance could do or receive, were it there present. But it is evident that if the substance of wine were there present, then some other liquid could be mingled with it.
Nevertheless there would be a different effect of such mixing both according to the form and according to the quantity of the liquid. For if sufficient liquid were mixed so as to spread itself all through the wine, then the whole would be a mixed substance. Now what is made up of things mixed is neither of them, but each passes into a third resulting from both: hence it would result that the former wine would remain no longer. But if the liquid added were of another species, for instance, if water were mixed, the species of the wine would be dissolved, and there would be a liquid of another species. But if liquid of the same species were added, of instance, wine with wine, the same species would remain, but the wine would not be the same numerically, as the diversity of the accidents shows: for instance, if one wine were white and the other red.
But if the liquid added were of such minute quantity that it could not permeate the whole, the entire wine would not be mixed, but only part of it, which would not remain the same numerically owing to the blending of extraneous matter: still it would remain the same specifically, not only if a little liquid of the same species were mixed with it, but even if it were of another species, since a drop of water blended with much wine passes into the species of wine (De Gener. i).