A guardian angel is an angel assigned to protect and guide a particular person. The belief in guardian angels can be traced throughout all antiquity. The concept of tutelary angels and their hierarchy was extensively developed in Christianity in the 5th century by Pseudo-Dionysius the Areopagite. The theology of angels, and tutelary spirits, has undergone many refinements since the 400s, and belief in both the East and the West is that guardian angels protect whichever person to whom God assigns them, 1]and present prayers to God on that person's behalf. The Catholic Church's calendar of saints and includes a memorial for the guardian angels on October 2.