As early as the fourth century the Christian Church had developed a profound belief in the existence of both good and evil angels,--“the foul fiends” and “bright squadrons” of Spenser’s lines,--the former ever tempting human beings to sin, and the indulgence of their lower natures; the latter inciting them to pursue good, forsaking evil and pressing forward to the perfect Christian life. This faith is devoutly maintained in the writings of the Fathers of the Church, in which we are also taught that angelic aid may be invoked in our need, and that a consciousness of the abiding presence of celestial beings should be a supreme solace to human sorrow and suffering. It remained for the theologians of the Middle Ages to exercise their fruitful imaginations in originating a systematic classification of the Orders of the Heavenly Host, and assigning to each rank its distinctive office. The warrant for these discriminations may seem insufficient to sceptical minds, but as their results are especially manifest in the works of the old masters, some knowledge of them is necessary to the student of Art; without it a large proportion of the famous religious pictures of the world are utterly void of meaning. Speaking broadly, this classification was based on that of St. Paul, when he speaks of “the principalities and powers in heavenly places,” and of “thrones and dominions;” on the account by Jude of the fall of the “angels which kept not their first estate;” on the triumphs of the Archangel Michael, and a few other texts of Scripture. Upon these premises the angelic host was divided into three hierarchies, and these again into nine choirs. The first hierarchy embraces seraphim, cherubim, and thrones, the first mention being sometimes given to the cherubim. Dionysius the Areopagite--to whom St. Paul confided all that he had seen, when transported to the seventh heaven--accords the first rank to the seraphim, while the familiar hymn of St. Ambrose has accustomed us to saying, “To Thee, cherubim and seraphim continually do cry.” Dante gives preference to Dionysius as an authority, and says of him: “For he had learn’d Both this and much beside of these our orbs From an eye-witness to Heaven’s mysteries.” The second hierarchy includes the dominations, virtues, and powers; the third, princedoms, archangels, and angels. The first hierarchy receives its glory directly from the Almighty, and transmits it to the second, which, in turn, illuminates the third, which is especially dedicated to the care and service of the human race. From the third hierarchy come the ministers and messengers of God; the second is composed of governors, and the first of councillors. The choristers of heaven are also angels, and the making of music is an important angelic duty.