5 In his second book he maintains a plurality of worlds; not, however, as Epicurus taught, many like ones existing at once, but a new one beginning each time that the old comes to an end. There was a world before this world of ours, and after it there will be first one and then another and so on in regular succession. He is in doubt whether one world shall be so completely similar to another as to leave no room for any difference between them, or whether one world shall never wholly be indistinguishable from another.
And again a little farther on he writes: “if, as the course of the discussion makes necessary, all things can live without body, all bodily existence shall be swallowed up and that which once has been made out of nothing shall again be reduced to nothing. And yet a time will come when its use will be once more necessary.” And in the same context: “but if, as reason and the authority of scripture show, this corruptible shall put on incorruption and this mortal shall put on immortality, death shall be swallowed up in victory and corruption in incorruption. And it may be that all bodily existence shall be removed, for it is only in this that death can operate.”
And a little farther on: “if these things are not contrary to the faith, it may be that we shall some day live in a disembodied state. Moreover, if only he is fully subject to Christ who is disembodied, and if all must be made subject to Him, we too shall lose our bodies when we become fully subject to Him.” And in the same passage: “if all are to be made subject to God, all shall lay aside their bodies; and then all bodily existence shall be brought to nought. But if through the fall of reasonable beings it is a second time required it will reappear.
For God has left souls to strive and struggle, to teach them that full and complete victory is to be attained not by their own efforts but by His grace. And so to my mind worlds vary with the sins which cause them, and those are exploded theories which maintain that all worlds are alike.” And again: “three conjectures occur to me with regard to the end; it is for the reader to determine which is nearest to the truth. For either we shall be bodiless when being made subject to Christ we shall be made subject to God and He shall be all in all; or as things made subject to Christ shall be with Christ Himself made subject to God and brought under one law, so all substance shall be refined into its most perfect form and rarified into æther which is a pure and uncompounded essence; or else the sphere which I have called motionless and all that it contains will be dissolved into nothing, and the sphere in which the antizone itself is contained shall be called 'good ground,' and that other sphere which in its revolution surrounds the earth and goes by the name of heaven shall be reserved for the abode of the saints.”
Source: Letters (New Advent)