This is truly the grand mystery of godliness: ‘God manifest in the flesh’ (1 Tim. 3:16), ‘For in him dwelleth all the fullness of the Godhead bodily’ (Col. 2:9), so that He is both God and man in the same person.
Perhaps this mode of exhibiting the divine attributes in humanity may be of unspeakable importance to all intelligent creatures in heaven. It may have given them an opportunity of knowing much more of God than they ever knew before, or could know in any other way. The doctrine of redemption is not only useful to the redeemed, but to all the hierarchy of heaven. No creature can know anything of the nature of God but what He is pleased to reveal; and the method by which He makes Himself known is by His works and dispensations.
Archibald Alexander, Brief Compendium, 55-56 cited in Garretson, ed., A Scribe Well-Trained: Archibald Alexander and the Life of Piety