De Moor IX:14: The Cause of the Goodness of the Good Angels, Part 1

These were created Good, not only Physically, but Ethically as rational creatures, or as furnished with Wisdom and Holiness worthy even of God.

But yet, in the next place, the habitual gifts were Mutably granted to them; so that those habits of Wisdom and Holiness granted to them by Creation were not regarded in themselves as Immutable.  It is not proven that they were Immutably Good by their very Creation:  our AUTHOR makes the contrary opinion especially probable:  α.  From this, that many Angels have actually fallen:  so that from the Event it is evident, that many were at least created as liable to a Fall:  but Scripture nowhere mentions that the difference between Angels was in Creation.  β.  From this, that Man was created as liable to Fall:  from which, it is admitted, it does not follow apodictically, that the matter stood in the same way in the case of Angels; at minimum, nevertheless, thence it is evident, that the example of other rational creatures, considered in their first state, does not hinder, but contrariwise more favors the opinion of our AUTHOR.  γ.  From this, that thus the Glory of the Divine Freedom, Grace, and Power appear to shine forth with greater intensity; in the permission of the Fall of some, who had been constituted in the same state with the rest, and in the powerful Preservation of the others.

Now, with respect to the Divine Decree, or of Preserving Grace, it is certain, that they were not able to fall:  but we do not here ascend to the Decree of God, with respect to which all things are to be said to be necessary; but a continual Concursus of God for the preservation of the primeval Goodness of the Elect Angels flowed, not from that Habitual Grace that was at first granted them, but from the Free Will of God.

Objection:  Scripture is silent concerning Grace added after Creation.  I Respond:  The Event sufficiently shows this, since no distinction is mentioned in the first Creation.  But, if you should ask, what was afterwards added to the Good Angels? I answer, the Immutability of the Goodness.