To show that quantity without the substance of which it is the quantity is not an impossibility, we must leave aside the idea that such a quantity is _a form inherent_ in the substance. For the quantity of the mass which alone is destined to become the first subject of all the other accidents is made up of a number of material parts, and therefore is not a form, but a certain amount of actual matter, and _fulfils the office of matter_, as S. Thomas recognizes, and not that of form, as Suarez and others after him have erroneously assumed. Now, it is evident that as no number can be conceived without units, so neither can a quantity of mass be conceived without its parts; and that, if such parts or units are substances, the quantity of the mass will be nothing less than a number of substances. So long, then, as such a quantity remains, it cannot cease to be a number of substances, unless, indeed, each of the units of which it is made up, _and which must always remain_, be supernaturally deprived of that which places them formally in the rank of substances. This is, therefore, what must be done, and what is really done by transubstantiation. When, in fact, the words of the consecration are pronounced, and the Sacred Body of our Lord is constituted under the sensible symbol _ad modum substantiæ_ (that is, not only substantially, but substantively), then the substantiality of every particle of the bread is superseded, and, so to say, supplanted by the new substance which lies under each of them, but which leaves intact the constituents of concrete quantity; for “the act and the power of substance,” and “whatever belongs to matter,” remains in each of them, as S. Thomas teaches, in accordance with the common doctrine of the ancient scholastics and of the fathers of the church. Thus the quantity of the bread remains the same as before, and _retains its formal and material constitution_, notwithstanding the substantial conversion of the bread into the Sacred Body of our Lord. Had the modern scholastics paid more attention to this last point, they would have seen that the species of bread is none of those natural accidents, whether forms or formalities, which found a place in Aristotle’s categories, but is a supernatural accident as perfectly constituted, in its own way, as substance itself, and therefore capable of being kept in existence by God without the help of a natural subject. The reader may infer from these remarks that the philosophical questions about _natural_ or predicamental accidents are altogether distinct from, and independent of, those concerning the sacramental species; and that therefore nothing that philosophers may say about _natural_ accidents can have any direct bearing on the explanation of the Eucharistic mystery.