Thomas Aquinas, Compendium of Theology

However, we should remember that the different kinds of material creatures are subordinated to man in different ways. Plants and animals serve man by aiding him in his weakness, in the sense that they supply him with food and clothing and transportation and like conveniences, whereby human feebleness is strengthened. But in the final state that comes after the resurrection all such defects will be eliminated from man. Men will no longer need food to eat, since they will be incorruptible, as we have pointed out. Nor will men need garments to cover their nakedness, because they will be clothed with the radiance of glory. Nor will they require animals to carry them, as they will be endowed with agility. Nor will they need medicines to keep them in health, since they will be impassible. In that state of final consummation, therefore, as we should expect, there will be no material creatures of this kind, namely, plants and animals and other like mixed bodies.

But the four elements, fire, air, water, and earth are for man not only as regards the utility of bodily life, but also as regards the composition of his body. The human body is made up of these elements. And so the elements have an essential ordination to the human body. Hence, when man is glorified in body and soul, the elements have to remain also, although they will be changed to a better condition of existence.

As for the heavenly bodies, their substance is not utilized for the support of man's corruptible life, and does not enter into the substance of the human frame. However, they serve man in the sense that by their beauty and enormous size they show forth the excellence of their Creator. For this reason man is often exhorted in Sacred Scripture to contemplate the heavenly bodies, so as to be moved by them to sentiments of reverence toward God. This is exemplified in Isaias 40:26: "Lift up your eyes on high, and see who hath created these things." And although, in the state of consummated perfection, man is not brought to the knowledge of God by a consideration of sensible creatures, since he sees God as He is in Himself, still it is pleasing and enjoyable for one who knows the cause to observe how the likeness of the cause shines forth in the effect. Thus a consideration of the divine goodness as mirrored in bodies, and particularly in the heavenly bodies, which appear to have a pre-eminence over other bodies, gives joy to the saints. Moreover, the heavenly bodies have some sort of essential relationship with the human body under the aspect of efficient causality, just as the elements have under the aspect of material causality: man generates man, and the sun, too, has some part in this operation. This, then, is another reason why the heavenly bodies should remain in existence.

The doctrine here advocated follows, not only from the relationship which various bodies have with man, but also from an examination of the natures of the material creatures we have been discussing. No object wanting in an intrinsic principle of incorruptibility ought to remain in the state that is characterized by incorruption. The heavenly bodies are incorruptible in whole and in part. The elements are incorruptible as wholes, but not as parts. Man is incorruptible in part, namely, in his rational soul, but not as a whole because the composite is dissolved by death. Animals and plants and all mixed bodies are incorruptible neither in whole nor in part. In the final state of incorruption, therefore, men and the elements and the heavenly bodies will fittingly remain, but not other animals or plants or mixed bodies.

We can argue reasonably to the same conclusion from the nature of the universe. Since man is a part of the material universe, the material universe should remain when man is brought to his final consummation; a part would seem to lack its proper perfection if it were to exist without the whole. On the other hand, the material universe cannot remain in existence without its essential parts. But the essential parts of the universe are the heavenly bodies and the elements, for the entire world machine is made up of them. Other bodies do not, apparently, pertain to the integrity of the material universe, but contribute rather to its adornment and beauty. They befit its changeable state in the sense that, with a heavenly body acting as efficient cause, and with the elements as material causes, animals and plants and minerals are brought into being. But in the state of final consummation another kind of adornment will be given to the elements, in keeping with their condition of incorruption. In that state, accordingly, there will remain men, elements, and heavenly bodies, but not animals or plants or minerals.