The elements do not change, for there is no chemical difference after consecration.

Which elements do not change? In every material thing there are two sets of elements quite distinct—substance and qualities. And no man has ever seen substance; he has seen qualities only. Thus I see the squareness of a block of iron, but it can become round, still remaining iron. I can feel its hardness, though it can become soft in the furnace, the substance being unchanged. If it be black, it can become red; if it be cold, it can become hot; if it be heavy, by great heat I can render it a vapor. The qualities, then, differ from the substance, or we could not change one without changing the other. And if we can change qualities without changing substance, God can certainly change substance without changing qualities. Any chemical differences are dependent upon qualities. Granted the permanence of the same accidental qualities the same chemical reactions will be apparent. Father Faber, whilst yet an Anglican, well said, “I am worried about the Roman doctrine because, whatever may be said of the proofs for it, I do not see how any man can disprove it. If they say that the substance changes, but that all appearances remain the same, then they say that something changes of which no man has any experience and yet which reason must postulate as the reality underlying all appearances and separate from them.” When you say that the elements do not change their chemical properties, I simply reply that the elements of external qualities do not change their chemical properties, and that no Catholic has ever imagined that they do. But the substance underlying those external appearances certainly does change. The fact that qualities remain unaltered is a fact of experience; the fact that the substance changes is revealed by God, and cannot be known in any other way. Yet is it not more than sufficiently guaranteed when God says so?

Radio Replies Volume 1 by Rev. Dr. Leslie Rumble MSC and Rev. Charles Mortimer Carty