The Principalities, Heavenly Messengers and Soldiers. The most influential Christian angelic hierarchy was that put forward by Pseudo-Dionysius the Areopagite (4th or 5th century) in his book De Coelesti Hierarchia (On the Celestial Hierarchy). He created a schema of three hierarchies (spheres or triads of angels), with each hierarchy containing three orders or choirs. Angels of the third sphere function as heavenly messengers and soldiers. The Principalities (Rulers) are shown wearing a crown and carrying a sceptre. Their duty also is said to be to carry out the orders given to them by the Dominions and bequeath blessings to the material world. Their task is to oversee groups of people. They are the educators and guardians of the realm of earth. Like beings related to the world of the germinal ideas, they are said to inspire living things to many things such as art or science. Taken from "The Hierarchy of the Blessed Angels. Their names, orders and offices the fall of Lucifer with his angels" by Thomas Heywood. Copper-plate engravings by Adam Islip, 1635.