In Summa Theologica suppl. q. 91, where St.Thomas Aquinas speaks of the quality of this world after the Last Judgement, a. 5 arg. 2 objects that plants, animals, and mineral bodies will be renewed. In reply to that objection (ad 2), he replies that animals, plants, mineral bodies and all other mixed bodies will not to be renewed and will not remain at the renewed world.
Objection 2. Further, just as the elements served man, so also did animals, plants and mineral bodies. But on account of this service the elements will be glorified. Therefore both animals and plants and mineral bodies will be glorified likewise.
Reply to Objection 2. Neither animals nor plants nor any other bodies merited anything by their services to man, since they lack free-will. However, certain bodies are said to be rewarded in so far as man merited that those things should be renewed which are adapted to be renewed. But plants and animals are not adapted to the renewal of incorruption, as stated above. Wherefore for this very reason man did not merit that they should be renewed, since no one can merit for another, or even for himself that which another or himself is incapable of receiving. Hence, granted even that dumb animals merited by serving man, it would not follow that they are to be renewed.
Now, according to the philosophies of St.Thomas, which mainly comes from Aristotle, mixed bodies means things that exist or come-to-be by some kind of composition of the elements. And St.Thomas clearly says that the only mixed body that will remain in the renewed world is man's body. And he says that only man's body, the elements and the heavenly bodies will remain in the renewed universe.
Suppl.q.91, article 5, ans. states,
Since the renewal of the world will be for man's sake it follows that it should be conformed to the renewal of man. Now by being renewed man will pass from the state of corruption to incorruptibility and to a state of everlasting rest, wherefore it is written (1 Corinthians 15:53): "This corruptible must put on incorruption, and this mortal must put on immortality"; and consequently the world will be renewed in such a way as to throw off all corruption and remain for ever at rest. Therefore it will be impossible for anything to be the subject of that renewal, unless it be a subject of incorruption. Now such are the heavenly bodies, the elements, and man. For the heavenly bodies are by their very nature incorruptible both as to their whole and as to their part: the elements are corruptible as to their parts but incorruptible as a whole: while men are corruptible both in whole and in part, but this is on the part of their matter not on the part of their form, the rational soul to wit, which will remain incorrupt after the corruption of man. on the other hand, dumb animals, plants, and minerals, and all mixed bodies, are corruptible both in their whole and in their parts, both on the part of their matter which loses its form, and on the part of their form which does not remain actually; and thus they are in no way subjects of incorruption. Hence they will not remain in this renewal, but those things alone which we have mentioned above.
But in Suppl.q.74,article 5, reply to objection 2, last two sentences, he says that the sea will remain as to containing salt, ie; mixed with salt:
If, however, the sea be taken literally we must reply that by the sea two things are to be understood, namely the substance of the waters, and their disposition, as containing salt and as to the movement of the waves. The sea will remain, not as to this second, but as to the first.
Apparently, he is saying that sea will remain as a mixed body, ie; mixed with salt, which is an earthly matter. But, as I noted above, he simultaneously says that the only mixed body that will remain is human body. Moreover, salt itself is a mixed body. He aparently says it will also remain.
Isn't this a contradiction?
How can it be explained?
Exactly, which bodies will remain in the renewed world?
If sea remains, then the land, made of soil, which is a diverse mixture of minerals, must also remain, must it not?
As I know, the element fire in St.Thomas'(and many others') philosophy corresponds to heat, air to the gases and water to the liquids. Then, some people say, earth must correspond to solids. Even if some solids are made of a uniform element such as diamond, which is purely made of the element carbon, the solids as a whole is not all the same thing, but mixtures of different chemical elements such as hydrogen, carbon etc. So, what is this pure earth according to medieval philosophers such as St.Thomas and Aristotle?
Also, he says all corruptible bodies will not remain and minerals are also corruptible bodies according to him. But, clearly, gold, quartz crystal etc are minerals and are not corruptible/decayable. Why does he say no other mixed body will remain, while we can find minerals(mixed bodies) that clearly don't decay?
How can these claims of St.Thomas be seen from the view point of modern science?
Sorry for a long question but I hope it is understandable:)