Whether bread can be converted into the body of Christ?

❌ Objection 1 : It seems that bread cannot be converted into the body of Christ. For conversion is a kind of change. But in every change there must be some subject, which from being previously in potentiality is now in act. because as is said in Phys. iii: "motion is the act of a thing existing in potentiality." But no subject can be assigned for the substance of the bread and of the body of Christ, because it is of the very nature of substance for it "not to be in a subject," as it is said in Praedic. iii. Therefore it is not possible for the whole substance of the bread to be converted into the body of Christ.

❌ Objection 2 : Further, the form of the thing into which another is converted, begins anew to inhere in the matter of the thing converted into it: as when air is changed into fire not already existing, the form of fire begins anew to be in the matter of the air; and in like manner when food is converted into non-pre-existing man, the form of the man begins to be anew in the matter of the food. Therefore, if bread be changed into the body of Christ, the form of Christ's body must necessarily begin to be in the matter of the bread, which is false. Consequently, the bread is not changed into the substance of Christ's body.

❌ Objection 3 : Further, when two things are diverse, one never becomes the other, as whiteness never becomes blackness, as is stated in Phys. i. But since two contrary forms are of themselves diverse, as being the principles of formal difference, so two signate matters are of themselves diverse, as being the principles of material distinction. Consequently, it is not possible for this matter of bread to become this matter whereby Christ's body is individuated, and so it is not possible for this substance of bread to be changed into the substance of Christ's body.