Whether the angels are incorruptible?

Objections

Objection 1 : It would seem that the angels are not incorruptible; for Damascene, speaking of the angel, says (De Fide Orth. ii, 3) that he is "an intellectual substance, partaking of immortality by favor, and not by nature."
Objection 2 : Further, Plato says in the Timaeus: "O gods of gods, whose maker and father am I: You are indeed my works, dissoluble by nature, yet indissoluble because I so will it." But gods such as these can only be understood to be the angels. Therefore the angels are corruptible by their nature
Objection 3 : Further, according to Gregory (Moral. xvi), "all things would tend towards nothing, unless the hand of the Almighty preserved them." But what can be brought to nothing is corruptible. Therefore, since the angels were made by God, it would appear that they are corruptible of their own nature.