Angelic hierarchies organize angels into different orders according to their functions and degrees of proximity to God. One of the most influential accounts was developed by Pseudo-Dionysius the Areopagite in De coelesti hierarchia (c. fifth–sixth century), the first systematic treatise devoted to angels. Drawing on both Biblical traditions and the Aristotelian concept of the Intelligences, Dionysius defined angels as incorporeal and immaterial beings associated with divine light. The Dionysian system divides angels into nine orders, arranged in three triads: Seraphim, Cherubim, and Thrones; Dominions, Virtues, and Powers; and Principalities, Archangels, and Angels. These orders reflect different degrees of proximity to God and different ways of receiving and transmitting divine knowledge and illumination. Unlike the Aristotelian Intelligences, which were responsible for the movement of the celestial spheres, Dionysian angels do not perform an active cosmological function. Their movement is instead understood as a spiritual and contemplative turning toward the divine. Dionysius’s hierarchical model profoundly shaped medieval theology, philosophy, literature, and art. His understanding of angels as immaterial beings and mediators of divine light became especially influential in the twelfth and thirteenth centuries and remained central to later discussions of angelic nature and order.