Angel, in the Greek language, means “messenger” or more literally “bringer of tidings”. The Bible lists several classes, or ranks, of angels. According to the work of the philosopher (Pseudo-)Dionysius the Areopagite there are nine classes of angels:
I. Counselors: 1. Seraphim, 2. Cherubim, 3. Thrones.
II. Governors: 4. Virtues, 5. Dominions, 6. Powers.
III. Messengers: 7. Principalities, 8. Archangels, 9. Angels.
“The order of these denominations is not the same in all authorities: according to the Greek formula, St. Bernard, and the Legenda Aurea, the Cherubim precede the Seraphim, and in the hymn of St. Ambrose they have also the precedence-‘To Thee, Cherubim and Seraphim continually do cry’, but the authority of St. Dionysius seems to be admitted as paramount, for, according to legend, he was the convert and intimate friend of St. Paul, and St. Paul, who had been transported to the seventh heaven, had made him acquainted with all he had there beheld.” 1
In ancient paintings glorifying the Holy Trinity, Jesus Christ, or the Virgin Mary, the various classes of angels are sometimes shown hovering above their heads. The