I. To the Question

4. I reply:

The authority of the Apostle [n.3] must absolutely be conceded.

5. But a distinction must be drawn between inward and outward mission. For according to common process and order, the superior mysteries of God are revealed to the superior before to the inferior; and thus the superior are sent interiorly to the inferior (by speaking to and illumining them) - and the others, the inferiors, are sent exteriorly to announce or expound to men the things revealed, and thus not all are commonly sent outwardly; and in this way can all the authorities be expounded that say they are sent outwardly.

6. However it seems that the supreme angels (or one or other of them) are sometimes sent outwardly:

For the incarnation of the Word was unknown to many of the angels before the time of the incarnation or passion of Christ, as is plain from Isaiah 63.1, where in the person of the inferior angels the question is asked, “Who is this who cometh from Edom, with dyed vestments, etc.” and Psalm 23.8, “Who is this king of glory?” (and the reply comes, “The Lord strong and mighty etc.”). It is also apparent from the Apostle Ephesians 3.8-10, “so that it may be known to Principalities and Powers through the Church     etc .” where Jerome’s Gloss says that “the angelic dignities did not know the aforesaid mystery in its purity until the passion of Christ had been completed and the preaching of the Apostles had been spread among the nations” - which mystery, however, was until that point “not unknown” to the greater angels according to Augustine’s Gloss. Now it is clear that it was not unknown to the angel sent to the blessed Virgin to make this announcement; therefore      he to whom this was laid open was one of the superiors -and not of the lowest to whom this sacred mystery was unknown.