II. To the Initial Arguments

418. To the first argument [n.323] I say that it is not of the essence of motion that it belong to such or such a being, nor of change that it be of something disposed in such a way, just as it is not of the essence of whiteness that it be of something possessing whiteness. But just as a form in settled being is in itself essentially of the sort it is, though it not be the form of anything, so motion is essentially a certain potential actuality, so to say, and change is a certain disposing differently, though it not belong to any [subject] denominated by this or that [disposition].

419. To the second [n.324] I say that just as the Philosopher conceded that a subject is necessary in the case of change or motion (because the subject would pre-exist the formal term and would be part of the formal term), so he said that the composite is the total term of this production. But for us the antecedent is not simply necessary.

420. To the third [n.325] I say that some change different from change in growth or diminution is possible in quantity, as division and being made continuous, and this as change in itself; but rarefaction and densification are change per accidens, and consequently the species [in the Eucharist] cannot grow or be diminished properly speaking, yet they can change from a lesser quantity to a greater quantity and conversely.