Objection 1. It would seem that by virtue of its subtlety, a glorified body will no longer need to be in an equal place. For the glorified bodies will be made like to the body of Christ according to Philippians 3:21. Now Christ's body is not bound by this necessity of being in an equal place: wherefore it is contained whole under the small or great dimensions of a consecrated host. Therefore the same will be true of the glorified bodies.
Objection 2. Further, the Philosopher proves (Phys. iv, 6), that two bodies are not in the same place, because it would follow that the greatest body would occupy the smallest place, since its various parts could be in the same part of the place: for it makes no difference whether two bodies or however many be in the same place. Now a glorified body will be in the same place with another body, as is commonly admitted. Therefore it will be possible for it to be in any place however small.
Objection 3. Further, even as a body is seen by reason of its color, so is it measured by reason of its quantity. Now the glorified body will be so subject to the spirit that it will be able at will to be seen, and not seen, especially by a non-glorified eye, as evidenced in the case of Christ. Therefore its quantity will be so subject to the spirit's will that it will be able to be in a little or great place, and to have a little or great quantity at will.
On the contrary, The Philosopher says (Phys. iv, text. 30) that "whatever is in a place occupies a place equal to itself." Now the glorified body will be in a place. Therefore it will occupy a place equal to itself.
Further, the dimensions of a place and of that which is in that place are the same, as shown in Phys. iv, text. 30,76,77. Therefore if the place were larger than that which is in the place the same thing would be greater and smaller than itself, which is absurd.
I answer that, A body is not related to place save through the medium of its proper dimensions, in respect of which a located body is confined through contact with the locating body. Hence it is not possible for a body to occupy a place smaller than its quantity, unless its proper quantity be made in some way less than itself: and this can only be understood in two ways. First, by a variation in quantity in respect of the same matter, so that in fact the matter which at first is subject to a greater quantity is afterwards subject to a lesser. Some have held this to be the case with the glorified bodies, saying that quantity is subject to them at will, so that when they list, they are able to have a great quantity, and when they list a small quantity. But this is impossible, because no movement affecting that which is intrinsic to a thing is possible without passion to the detriment [Cf. I-II, 22, 1; I-II, 41, 1] of its substance. Hence in incorruptible, i.e. heavenly, bodies, there is only local movement, which is not according to something intrinsic. Thus it is clear that change of quantity in respect of matter would be incompatible with the impassibility and incorruptibility of a glorified body. Moreover, it would follow that a glorified body would be sometimes rarer and sometimes denser, because since it cannot be deprived of any of its matter, sometimes the same matter would be under great dimensions and sometimes under small dimensions, and thus it would be rarefied and densified, which is impossible. Secondly, that the quantity of a glorified body become smaller than itself may be understood by a variation of place; so, to wit, that the parts of a glorified body insinuate themselves into one another, so that it is reduced in quantity however small it may become. And some have held this to be the case, saying that by reason of its subtlety a glorified body will be able to be in the same place with a non-glorified body: and that in like manner its parts can be one within the other, so much so that a whole glorified body will be able to pass through the minutest opening in another body: and thus they explain how Christ's body came out of the Virgin's womb; and how it went into His disciples, the doors being shut. But this is impossible; both because the glorified body will not be able, by reason of its subtlety, to be in the same place with another body, and because, even if it were able to be in the same place with another body, this would not be possible if the other were a glorified body, as many say; and again because this would be inconsistent with the right disposition of the human body, which requires the parts to be in a certain fixed place and at a certain fixed distance from one another. Wherefore this will never happen, not even by a miracle. Consequently we must say that the glorified body will always be in a place equal to itself.
Reply to Objection 1. Christ's body is not locally in the Sacrament of the Altar, as stated above (Sent. iv, D, 10, 1, 1, ad 5; III, 77, 5).
Reply to Objection 2. The Philosopher's argument is that for the same reason one part might permeate another. But this permeation of the parts of a glorified body into one another is impossible, as stated above. Therefore the objection does not prove.
Reply to Objection 3. A body is seen because it acts on the sight: but that it does or does not act on the sight causes no change in the body. Hence it is not unfitting, if it can be seen when it will, and not seen when it will [Cf. III, 55, 4]. On the other hand, being in a place is not an action proceeding from a body by reason of its quantity, as being seen is by reason of its color. Consequently the comparison fails.
Source: Summa Theologica (New Advent)