Reply Obj. 5: The name "Seraphim" does not come from charity only, but from the excess of charity, expressed by the word ardor or fire. Hence Dionysius (Coel. Hier. vii) expounds the name "Seraphim" according to the properties of fire, containing an excess of heat. Now in fire we may consider three things. First, the movement which is upwards and continuous. This signifies that they are borne inflexibly towards God. Secondly, the active force which is "heat," which is not found in fire simply, but exists with a certain sharpness, as being of most penetrating action, and reaching even to the smallest things, and as it were, with superabundant fervor; whereby is signified the action of these angels, exercised powerfully upon those who are subject to them, rousing them to a like fervor, and cleansing them wholly by their heat. Thirdly we consider in fire the quality of clarity, or brightness; which signifies that these angels have in themselves an inextinguishable light, and that they also perfectly enlighten others.
In the same way the name "Cherubim" comes from a certain excess of knowledge; hence it is interpreted "fulness of knowledge," which Dionysius (Coel. Hier. vii) expounds in regard to four things: the perfect vision of God; the full reception of the Divine Light; their contemplation in God of the beauty of the Divine order; and in regard to the fact that possessing this knowledge fully, they pour it forth copiously upon others.
Reply Obj. 6: The order of the "Thrones" excels the inferior orders as having an immediate knowledge of the types of the Divine works; whereas the "Cherubim" have the excellence of knowledge and the "Seraphim" the excellence of ardor. And although these two excellent attributes include the third, yet the gift belonging to the "Thrones" does not include the other two; and so the order of the "Thrones" is distinguished from the orders of the "Cherubim" and the "Seraphim." For it is a common rule in all things that the excellence of the inferior is contained in the superior, but not conversely. But Dionysius (Coel. Hier. vii) explains the name "Thrones" by its relation to material seats, in which we may consider four things. First, the site; because seats are raised above the earth, and to the angels who are called "Thrones" are raised up to the immediate knowledge of the types of things in God. Secondly, because in material seats is displayed strength, forasmuch as a person sits firmly on them. But here the reverse is the case; for the angels themselves are made firm by God. Thirdly, because the seat receives him who sits thereon, and he can be carried thereupon; and so the angels receive God in themselves, and in a certain way bear Him to the inferior creatures. Fourthly, because in its shape, a seat is open on one side to receive the sitter; and thus are the angels promptly open to receive God and to serve Him. _______________________
SIXTH ARTICLE [I, Q. 108, Art. 6]
Whether the Grades of the Orders Are Properly Assigned?
Objection 1: It would seem that the grades of the orders are not properly assigned. For the order of prelates is the highest. But the names of "Dominations," "Principalities," and "Powers" of themselves imply prelacy. Therefore these orders ought not to be supreme.
Obj. 2: Further, the nearer an order is to God, the higher it is. But the order of "Thrones" is the nearest to God; for nothing is nearer to the sitter than the seat. Therefore the order of the "Thrones" is the highest.
Obj. 3: Further, knowledge comes before love, and intellect is higher than will. Therefore the order of "Cherubim" seems to be higher than the "Seraphim."
Obj. 4: Further, Gregory (Hom. xxiv in Evang.) places the "Principalities" above the "Powers." These therefore are not placed immediately above the Archangels, as Dionysius says (Coel. Hier. ix).
On the contrary, Dionysius (Coel. Hier. vii), places in the highest hierarchy the "Seraphim" as the first, the "Cherubim" as the middle, the "Thrones" as the last; in the middle hierarchy he places the "Dominations," as the first, the "Virtues" in the middle, the "Powers" last; in the lowest hierarchy the "Principalities" first, then the "Archangels," and lastly the "Angels."