Reply Obj. 1: That is the text of the old translation, which is amended in the new one, and runs thus: "furthermore they," that is to say the angels, "knew their own powers": instead of which the old translation read—"and furthermore they do not know their own powers." Although even the letter of the old translation might be kept in this respect, that the angels do not know their own power perfectly; according as it proceeds from the order of the Divine Wisdom, Which to the angels is incomprehensible.
Reply Obj. 2: We have no knowledge of single corporeal things, not because of their particularity, but on account of the matter, which is their principle of individuation. Accordingly, if there be any single things subsisting without matter, as the angels are, there is nothing to prevent them from being actually intelligible.
Reply Obj. 3: It belongs to the intellect, in so far as it is in potentiality, to be moved and to be passive. Hence this does not happen in the angelic intellect, especially as regards the fact that he understands himself. Besides the action of the intellect is not of the same nature as the action found in corporeal things, which passes into some other matter. _______________________
SECOND ARTICLE [I, Q. 56, Art. 2]
Whether One Angel Knows Another?
Objection 1: It would seem that one angel does not know another. For the Philosopher says (De Anima iii, text. 4), that if the human intellect were to have in itself any one of the sensible things, then such a nature existing within it would prevent it from apprehending external things; as likewise, if the pupil of the eye were colored with some particular color, it could not see every color. But as the human intellect is disposed for understanding corporeal things, so is the angelic mind for understanding immaterial things. Therefore, since the angelic intellect has within itself some one determinate nature from the number of such natures, it would seem that it cannot understand other natures.
Obj. 2: Further, it is stated in De Causis that "every intelligence knows what is above it, in so far as it is caused by it; and what is beneath it, in so far as it is its cause." But one angel is not the cause of another. Therefore one angel does not know another.
Obj. 3: Further, one angel cannot be known to another angel by the essence of the one knowing; because all knowledge is effected by way of a likeness. But the essence of the angel knowing is not like the essence of the angel known, except generically; as is clear from what has been said before (Q. 50, A. 4; Q. 55, A. 1, ad 3). Hence, it follows that one angel would not have a particular knowledge of another, but only a general knowledge. In like manner it cannot be said that one angel knows another by the essence of the angel known; because that whereby the intellect understands is something within the intellect; whereas the Trinity alone can penetrate the mind. Again, it cannot be said that one angel knows the other by a species; because that species would not differ from the angel understood, since each is immaterial. Therefore in no way does it appear that one angel can understand another.
Obj. 4: Further, if one angel did understand another, this would be either by an innate species; and so it would follow that, if God were now to create another angel, such an angel could not be known by the existing angels; or else he would have to be known by a species drawn from things; and so it would follow that the higher angels could not know the lower, from whom they receive nothing. Therefore in no way does it seem that one angel knows another.
On the contrary, We read in De Causis that "every intelligence knows the things which are not corrupted."