On the End of the World
4 And now, as we find the apostle making mention of a spiritual body, let us inquire, to the best of our ability, what idea we are to form of such a thing. So far, then, as our understanding can grasp it, we consider a spiritual body to be of such a nature as ought to be inhabited not only by all holy and perfect souls, but also by all those creatures which will be liberated from the slavery of corruption. Respecting the body also, the apostle has said, “We have a house not made with hands, eternal in the heavens,” i.e., in the mansions of the blessed. And from this statement we may form a conjecture, how pure, how refined, and how glorious are the qualities of that body, if we compare it with those which, although they are celestial bodies, and of most brilliant splendour, were nevertheless made with hands, and are visible to our sight. But of that body it is said, that it is a house not made with hands, but eternal in the heavens. Since, then, those things “which are seen are temporal, but those things which are not seen are eternal,” all those bodies which we see either on earth or in heaven, and which are capable of being seen, and have been made with hands, but are not eternal, are far excelled in glory by that which is not visible, nor made with hands, but is eternal. From which comparison it may be conceived how great are the comeliness, and splendour, and brilliancy of a spiritual body; and how true it is, that “eye has not seen, nor ear heard, nor has it entered into the heart of man to conceive, what God has prepared for them that love Him.” We ought not, however, to doubt that the nature of this present body of ours may, by the will of God, who made it what it is, be raised to those qualities of refinement, and purity, and splendour (which characterize the body referred to), according as the condition of things requires, and the deserts of our rational nature shall demand. Finally, when the world required variety and diversity, matter yielded itself with all docility throughout the diverse appearances and species of things to the Creator, as to its Lord and Maker, that He might educe from it the various forms of celestial and terrestrial beings. But when things have begun to hasten to that consummation that all may be one, as the Father is one with the Son, it may be understood as a rational inference, that where all are one, there will no longer be any diversity.
5. The last enemy, moreover, who is called death, is said on this account to be destroyed, that there may not be anything left of a mournful kind when death does not exist, nor anything that is adverse when there is no enemy. The destruction of the last enemy, indeed, is to be understood, not as if its substance, which was formed by God, is to perish, but because its mind and hostile will, which came not from God, but from itself, are to be destroyed. Its destruction, therefore, will not be its non-existence, but its ceasing to be an enemy, and (to be) death. For nothing is impossible to the Omnipotent, nor is anything incapable of restoration to its Creator: for He made all things that they might exist, and those things which were made for existence cannot cease to be. For this reason also will they admit of change and variety, so as to be placed, according to their merits, either in a better or worse position; but no destruction of substance can befall those things which were created by God for the purpose of permanent existence. For those things which agreeably to the common opinion are believed to perish, the nature either of our faith or of the truth will not permit us to suppose to be destroyed. Finally, our flesh is supposed by ignorant men and unbelievers to be destroyed after death, in such a degree that it retains no relic at all of its former substance. We, however, who believe in its resurrection, understand that a change only has been produced by death, but that its substance certainly remains; and that by the will of its Creator, and at the time appointed, it will be restored to life; and that a second time a change will take place in it, so that what at first was flesh (formed) out of earthly soil, and was afterwards dissolved by death, and again reduced to dust and ashes (“For dust you are,” it is said, “and to dust shall you return”), will be again raised from the earth, and shall after this, according to the merits of the indwelling soul, advance to the glory of a spiritual body.
Source: De Principiis (New Advent)