Alberti Magni Opera Omnia, Vol. XXXVII

"...and of those subject, it is reductive and active and exemplary, as if reheating them and reviving them into a similar heat and fire from heaven, and as a holocaust, purgative, and unveiled, and inextinguishable, always having such a light-formed and illuminative property, the pursuer and manifestor of every shadowy obscuration." St. Dionysius, On the Celestial Hierarchy, Chapter 7. That highest perfection of charity which is described here, ascending to God and descending to the neighbor, was completed in the most blessed Virgin in this annunciation. Therefore, it is manifest that it ought to have been done through the Seraphim.

Item, it seems that all three first orders ought to have been sent.

For the first order takes its name from charity, the second from cognition, the third from power; but all these things are shown here in their highest degree; therefore, it ought to have been done through all three. The minor premise is evident through John of Damascus, who says: "He manifests a great sea of clemency around Himself. For the Architect, Creator, and Lord Himself, for the sake of His own workmanship, took on [a] workmanship, becoming a teacher by [His] work. And because the enemy had seduced man with the hope of divinity, he is deceived under the pretext of flesh. And the goodness and wisdom and justice and power of God are demonstrated simultaneously. Goodness: because He did not despise the infirmity of His own workmanship and creation, but, pitying the fallen one, He reached out His hand to him. Justice: because when man was conquered, He did not make the tyrant be conquered by any other than man. Nor did He snatch man from death by violence: but the one whom death had formerly reduced into servitude through sin, this good and just One made a victor again, and repaired like with like, which was the work needed. Wisdom: because He found the most decent solution to a matter of extreme doubt and difficulty." St. John of Damascus, On the Orthodox Faith, Book III, Chapter 1. Therefore, since this is announced here, in which the property of all three of these orders is demonstrated, it seems that all three orders ought to have been sent.

However, it seems that all the Angels ought to have been sent: because just as the one announcing is related to the one receiving, and the business is related to the negotiation, so the messenger ought to be related to the message: but all other things here were in their highest degree; therefore, the quality of the messenger also ought to have been in its highest degree here. The minor premise is evident: for there could not be a greater one announcing than God, who was doing the announcing, nor a greater one receiving than the one who was receiving it, who was the supreme [member] in the Church Militant, and the business could not be greater or more arduous in utility, dignity, or novelty: therefore, if all other things were at their highest here, the quality of the messenger ought also to have been at its highest; but plurality increases the quality of a messenger: for it is more solemn to send many and great ones than just any one; therefore, the more messengers there are who are great and solemn, the more solemnized the annunciation is: therefore, if the whole [event] ought to be in its highest state, it was necessary that all of them be sent.

It seems, however, that the messenger ought to have been even higher, namely, the uncreated Holy Spirit.