Powers is one of the nine choirs, or orders, of angels described in The Celestial Hierarchy, a treatise written around the late fifth or early sixth century by the anonymous Christian author known as Pseudo-Dionysius the Areopagite. That work arranges the angels in three triads: the highest of Seraphim, Cherubim and Thrones; the middle of Dominions, Virtues and Powers; and the lowest of Principalities, Archangels and Angels. The scheme drew together the various ranks named in scripture, the seraphim of Isaiah, the cherubim of Genesis and Ezekiel, and the thrones, dominions, principalities and powers listed in the Pauline epistles, into a single ordered hierarchy that became standard in medieval Christian theology and was carried further by Thomas Aquinas and by Dante. This entry describes Powers as a figure of that documented theological and literary tradition.
Powers translates exousiai, "authorities," the term paired with dynameis in Ephesians 1:21 and again, alongside principalities, in Ephesians 3:10 and 6:12, where it names the "spiritual forces of evil in the heavenly realms" against which Paul says Christians contend, a usage that shows the same Greek vocabulary describing both faithful and fallen powers depending on context. Aquinas gives this choir the specific office of restraining demonic power and holding the created order against chaos, a martial function distinct from the miracle-working he assigns to Virtues immediately above.