Pseudo-Dionysius (On the Celestial Hierarchy) and Saint Thomas Aquinas (Summa Theologiae) drew on passages from the New Testament, specifically Ephesians  and Colossians 1:16, to develop a schema of three Hierarchies, Spheres or Triads of angels, with each Hierarchy containing three Orders or Choirs.
These theological works by Pseudo-Dionysius (On the Celestial Hierarchy) and Saint Thomas Aquinas (Summa Theologiae) drew upon New Testament passages in Ephesians  and Colossians 1:16 to create a hierarchical system of three angelic levels, each comprising three ranks or choirs.