In matters that are so obscure and far beyond our vision, we find in Holy Scripture passages which can be interpreted in very different ways without prejudice to the faith we have received. In such cases, we should not rush in headlong and so firmly take our stand on one side that, if further progress in the search for truth justly undermines this position, we too fall with it.
What then, is correctness of speech but the maintenance of the practice of others, as established by the authority of ancient speakers? But the weaker men are, the more they are troubled by such matters. Their weakness stems from a desire to appear learned, not with a knowledge of things, by which we are edified, but with a knowledge of signs, by which it is difficult not to be puffed up in some way; even a knowledge of things often makes people boastful, unless their necks are held down by the Lord's yoke.
The bread that you see on the altar is the Body of Christ as soon as it is sanctified by God's word. The chalice, or better what is contained in the chalice, is the Blood of Christ as soon as it is sanctified by God's word