Principalities - highest angels of Third Sphere. Their duty to carry out the orders given to them by the Dominions and bequeath blessings to the material world. As beings related to the world of the germinal ideas, they are said to inspire living things to many things such as art or science. Drawn in SAI. Lineart is here: [link]
Official? ^__^ Haha, sorry, it sounds funny... I used encyclopedia, which stated Pseudo-Dionysius the Areopagite (4th century) and his book "The Celestial Hierarchy" as sourse.