Summa Theologica, by St. Thomas Aquinas, [1947], at sacred-texts.com
We must now consider the clarity of the beatified bodies at the resurrection. Under this head there are three points of inquiry:
(1) Whether there will be clarity in the glorified bodies?
(2) Whether this clarity will be visible to the non-glorified eye?
(3) Whether a glorified body will of necessity be seen by a non-glorified body?
Objection 1: It would seem that clarity is unbecoming to the glorified body. Because according to Avicenna (Natural. vi, 2), "every luminous body consists of transparent parts." But the parts of a glorified body will not be transparent, since in some of them, such as flesh and bones, earth is predominant. Therefore glorified bodies are not lightsome.
Objection 2: Further, every lightsome body hides one that is behind it; wherefore one luminary behind another is eclipsed, and a flame of fire prevents one seeing what is behind it. But the glorified bodies will not hide that which is within them, for as Gregory says on Job 28:17, "Gold or crystal cannot equal it" (Moral. xviii, 48). "There," that is in the heavenly country, "the grossness of the members will not hide one's mind from another's eyes, and the very harmony of the body will be evident to the bodily sight." Therefore those bodies will not be lightsome.
Objection 3: Further, light and color require a contrary disposition in their subject, since "light is the extreme point of visibility in an indeterminate body; color, in a determinate body" (De Sensu et Sensato iii). But glorified bodies will have color, for as Augustine says (De Civ. Dei xxii, 3), "the body's beauty is harmony of parts with a certain charm of color": and it will be impossible for the glorified bodies to lack beauty. Therefore the glorified bodies will not be lightsome.
Objection 4: Further, if there be clarity in the glorified bodies, it will need to be equal in all the parts of the body, just as all the parts will be equally impassible, subtle and agile. But this is not becoming, since one part has a greater disposition to clarity than another, for instance the eye than the hand, the spirits [*"Animalem," as though it were derived from "animus"---the mind. Cf. FS, Q[50], A[1],3m; FS, Q[52], A[1] ,3m] than the bones, the humors than the flesh or nerves. Therefore it would seem unfitting for those bodies to be lightsome.
On the contrary, It is written (Mat. 13:43): "The just shall shine as the sun in the kingdom of their Father," and (Wis. 3:7): "The just shall shine, and shall run to and fro like sparks among the reeds."
Further, it is written (1 Cor. 15:43): "It is sown in dishonor, it shall rise in glory," which refers to clarity, as evidenced by the previous context where the glory of the rising bodies is compared to the clarity of the stars. Therefore the bodies of the saints will be lightsome.
I answer that, It is necessary to assert that after the resurrection the bodies of the saints will be lightsome, on account of the authority of Scripture which makes this promise. But the cause of this clarity is ascribed by some to the fifth or heavenly essence, which will then predominate in the human body. Since, however, this is absurd, as we have often remarked (Q[84], A[1]), it is better to say that this clarity will result from the overflow of the soul's glory into the body. For whatever is received into anything is received not according to the mode of the source whence it flows, but according to the mode of the recipient. Wherefore clarity which in the soul is spiritual is received into the body as corporeal. And consequently according to the greater clarity of the soul by reason of its greater merit, so too will the body differ in clarity, as the Apostle affirms (1 Cor. 15:41). Thus in the glorified body the glory of the soul will be known, even as through a crystal is known the color of a body contained in a crystal vessel, as Gregory says on Job 28:17, "Gold or crystal cannot equal it."
Reply to Objection 1: Avicenna is speaking of a body that has clarity through the nature of its component parts. It is not thus but rather by merit of virtue that the glorified body will have clarity.
Reply to Objection 2: Gregory compares the glorified body to gold on account of clarity, and to crystal on account of its transparency. Wherefore seemingly we should say that they will be both transparent and lightsome; for that a lightsome body be not transparent is owing to the fact that the clarity of that body results from the density of the lightsome parts, and density is opposed to transparency. Then, however, clarity will result from another cause, as stated above: and the density of the glorified body will not deprive it of transparency, as neither does the density of a crystal deprive crystal.
Some, on the other hand, say that they are compared to crystal, not because they are transparent, but on account of this likeness, for as much as that which is enclosed in crystal is visible, so the glory of the soul enclosed in the glorified body will not be hidden. But the first explanation is better, because it safeguards better the dignity of the glorified body, and is more consistent with the words of Gregory.
Reply to Objection 3: The glory of the body will not destroy nature but will perfect it. Wherefore the body will retain the color due to it by reason of the nature of its component parts, but in addition to this it will have clarity resulting from the soul's glory. Thus we see bodies which have color by their nature aglow with the resplendence of the sun, or from some other cause extrinsic or intrinsic.
Reply to Objection 4: Even as the clarity of glory will overflow from the soul into the body according to the mode of the body, and is there otherwise than in the soul, so again it will overflow into each part of the soul according to the mode of that part. Hence it is not unreasonable that the different parts should have clarity in different ways, according as they are differently disposed thereto by their nature. Nor is there any comparison with the other gifts of the body, for the various parts of the body are not differently disposed in their regard.
Objection 1: It would seem that the clarity of the glorified body is invisible to the non-glorified eye. For the visible object should be proportionate to the sight. But a non-glorified eye is not proportionate to see the clarity of glory, since this differs generically from the clarity of nature. Therefore the clarity of the glorified body will not be seen by a non-glorified eye.
Objection 2: Further, the clarity of the glorified body will be greater than the clarity of the sun is now, since the clarity of the sun also will then be greater than it is now, according to Is. 30:26, and the clarity of the glorified body will be much greater still, for which reason the sun and the entire world will receive greater clarity. Now a non-glorified eye is unable to gaze on the very orb of the sun on account of the greatness of its clarity. Therefore still less will it be able to gaze on the clarity of a glorified body.
Objection 3: Further, a visible object that is opposite the eyes of the seer must needs be seen, unless there be some lesion to the eye. But the clarity of a glorified body that is opposite to non-glorified eyes is not necessarily seen by them: which is evident in the case of the disciples who saw our Lord's body after the resurrection, without witnessing its clarity. Therefore this clarity will be invisible to a non-glorified eye.
On the contrary, A gloss on Phil. 3:21, "Made like to the body of His glory," says: "It will be like the clarity which He had in the Transfiguration." Now this clarity was seen by the non-glorified eyes of the disciples. Therefore the clarity of the glorified body will be visible to non-glorified eyes also.
Further, the wicked will be tortured in the judgment by seeing the glory of the just, according to Wis. 5:2. But they would not fully see their glory unless they gazed on their clarity. Therefore, etc.
I answer that, Some have asserted that the clarity of the glorified body will not be visible to the non-glorified eye, except by a miracle. But this is impossible, unless this clarity were so named equivocally, because light by its essence has a natural tendency to move the sight, and sight by its essence has a natural tendency to perceive light, even as the true is in relation to the intellect, and the good to the appetite. Wherefore if there were a sight altogether incapable of perceiving a light, either this sight is so named equivocally, or else this light is. This cannot be said in the point at issue, because then nothing would be made known to us when we are told that the glorified bodies will be lightsome: even so a person who says that a dog [*The dog star] is in the heavens conveys no knowledge to one who knows no other dog than the animal. Hence we must say that the clarity of a glorified body is naturally visible to the non-glorified eye.
Reply to Objection 1: The clarity of glory will differ generically from the clarity of nature, as to its cause, but not as to its species. Hence just as the clarity of nature is, by reason of its species, proportionate to the sight, so too will the clarity of glory be.
Reply to Objection 2: Just as a glorified body is not passible to a passion of nature but only to a passion of the soul [*Cf. Q[82], A[1]], so in virtue of its property of glory it acts only by the action of the soul. Now intense clarity does not disturb the sight, in so far as it acts by the action of the soul, for thus it rather gives delight, but it disturbs it in so far as it acts by the action of nature by heating and destroying the organ of sight, and by scattering the spirits* asunder. [*"Animalem," as though it were derived from "animus"---the mind. Cf. FS, Q[50], A[1] ,3m; FS, Q[52], A[1],3m.] Hence, though the clarity of a glorified body surpasses the clarity of the sun, it does not by its nature disturb the sight but soothes it: wherefore this clarity is compared to the jasper-stone (Apoc. 21:11).
Reply to Objection 3: The clarity of the glorified body results from the merit of the will and therefore will be subject to the will, so as to be seen or not seen according to its command. Therefore it will be in the power of the glorified body to show forth its clarity or to hide it: and this was the opinion of Praepositivus.
Objection 1: It would seem that a glorified body will be necessarily seen by a non-glorified body. For the glorified bodies will be lightsome. Now a lightsome body reveals itself and other things. Therefore the glorified bodies will be seen of necessity.
Objection 2: Further, every body which hides other bodies that are behind it is necessarily perceived by the sight, from the very fact that the other things behind it are hidden. Now the glorified body will hide other bodies that are behind it from being seen, because it will be a colored body. Therefore it will be seen of necessity.
Objection 3: Further, just as quantity is something in a body, so is the quality whereby a body is seen. Now quantity will not be subject to the will, so that the glorified body be able to be of greater or smaller quantity. Therefore neither will the quality of visibility be subject to the will, so that a body be able not to be seen.
On the contrary, our body will be glorified in being made like to the body of Christ after the resurrection. Now after the resurrection Christ's body was not necessarily seen; in fact it vanished from the sight of the disciples at Emmaus (Lk. 24:31). Therefore neither will the glorified body be necessarily seen.
Further, there the body will be in complete obedience to the will. Therefore as the soul lists the body will be visible or invisible.
I answer that, A visible object is seen, inasmuch as it acts on the sight. Now there is no change in a thing through its acting or not acting on an external object. Wherefore a glorified body may be seen or not seen without any property pertaining to its perfection being changed. Consequently it will be in the power of a glorified soul for its body to be seen or not seen, even as any other action of the body will be in the soul's power; else the glorified body would not be a perfectly obedient instrument of its principal agent.
Reply to Objection 1: This clarity will be obedient to the glorified body so that this will be able to show it or hide it.
Reply to Objection 2: A body's color does not prevent its being transparent except in so far as it affects the sight, because the sight cannot be affected by two colors at the same time, so as to perceive them both perfectly. But the color of the glorified body will be completely in the power of the soul, so that it can thereby act or not act on the sight. Hence it will be in its power to hide or not to hide a body that is behind it.
Reply to Objection 3: Quantity is inherent to the glorified body itself, nor would it be possible for the quantity to be altered at the soul's bidding without the glorified body suffering some alteration incompatible with its impassibility. Hence there is no comparison between quantity and visibility, because even this quality whereby it is visible cannot be removed at the soul's bidding, but the action of that quality will be suspended, and thus the body will be hidden at the soul's command.