Secondly, because if the substantial form of the bread were to remain, it would remain either in matter, or separated from matter. The first cannot be, for if it were to remain in the matter of the bread, then the whole substance of the bread would remain, which is against what was said above (A. 2). Nor could it remain in any other matter, because the proper form exists only in its proper matter. But if it were to remain separate from matter, it would then be an actually intelligible form, and also an intelligence; for all forms separated from matter are such.
Thirdly, it would be unbefitting this sacrament: because the accidents of the bread remain in this sacrament, in order that the body of Christ may be seen under them, and not under its proper species, as stated above (A. 5).
And therefore it must be said that the substantial form of the bread does not remain.
Reply Obj. 1: There is nothing to prevent art from making a thing whose form is not an accident, but a substantial form; as frogs and serpents can be produced by art: for art produces such forms not by its own power, but by the power of natural energies. And in this way it produces the substantial forms of bread, by the power of fire baking the matter made up of flour and water.
Reply Obj. 2: The soul is the form of the body, giving it the whole order of perfect being, i.e. being, corporeal being, and animated being, and so on. Therefore the form of the bread is changed into the form of Christ's body, according as the latter gives corporeal being, but not according as it bestows animated being.
Reply Obj. 3: Some of the operations of bread follow it by reason of the accidents, such as to affect the senses, and such operations are found in the species of the bread after the consecration on account of the accidents which remain. But some other operations follow the bread either by reason of the matter, such as that it is changed into something else, or else by reason of the substantial form, such as an operation consequent upon its species, for instance, that it "strengthens man's heart" (Ps. 103:15); and such operations are found in this sacrament, not on account of the form or matter remaining, but because they are bestowed miraculously upon the accidents themselves, as will be said later (Q. 77, A. 3, ad 2, 3; AA. 5, 6). _______________________
SEVENTH ARTICLE [III, Q. 75, Art. 7]
Whether This Change Is Wrought Instantaneously?
Objection 1: It seems that this change is not wrought instantaneously, but successively. For in this change there is first the substance of bread, and afterwards the substance of Christ's body. Neither, then, is in the same instant, but in two instants. But there is a mid-time between every two instants. Therefore this change must take place according to the succession of time, which is between the last instant in which the bread is there, and the first instant in which the body of Christ is present.
Obj. 2: Further, in every change something is in becoming and something is in being. But these two things do not exist at the one time for, what is in becoming, is not yet, whereas what is in being, already is. Consequently, there is a before and an after in such change: and so necessarily the change cannot be instantaneous, but successive.